July 14, 2017

Mr. Jim B. Rosenberg

Senior Assistant Chief Accountant

Office of Healthcare and Insurance

Securities and Exchange Commission

Mail Stop 4546

100 F Street N.E

Washington, D.C. 20549

Re: The Hanover Insurance Group, Inc.

Form 10-Kfor the Fiscal Year Ended December 31, 2016

Filed February 22, 2017

FileNo. 001-13754

Dear Mr. Rosenberg:

This letter provides the responses of The Hanover Insurance Group, Inc. (the “Company”) to the comment of the staff (the “Staff”) of the Division of Corporation Finance of the Securities and Exchange Commission (the “Commission”) regarding the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 (the “Form 10-K”) in your June 20, 2017 letter to Jeffrey Farber, the Company’s Executive Vice President and Chief Financial Officer (the “Comment Letter”).

The Staff’s comment is included below in italics, followed by the Company’s response.

Comment & Response

Notes to Consolidated Financial Statements

Note 17: Liabilities for Outstanding Claims, Lossesand LossAdjustment Expenses, page 108

1. We have reviewed your response to prior comment 5in ourApril 28, 2017 letter regarding why you did notprovide any claims development tables underASC 944-40-50-4B for the “otherlines”componentofyour “Commercial Lines and other.” You assert in your response that thereare20 product lines within the “other lines” component, noneof which areindividually significant.  In addition tothese “other lines,” we observe that you did notprovide claims development tables for certain lines within personal auto and for homeowners.  The exclusion of tables for the20 productlines within the “other lines” component,certain lineswithin personal auto,and homeowners results in the exclusion ofinformation about claimsincurredand paid and/orclaimsdevelopmentthat is substantial to the respective consolidated totals.As such, we question your application of ASC 944-40-50-4H (both aggregation/disaggregation andthedetermination of insignificant categories)as itappearsto haveresultedin the disclosures requiredby ASC 944-40-50-4B and 50-4D not providing sufficient information to allow users toassess the

hanover.com	Hanover Insurance Group, Inc.
	440 Lincoln Street, Worcester, MA, 01653

amount, timing and uncertainty of cash flows arising froma substantial portion of your insurance contracts andthe related development of yourlossreserveestimates as stipulatedinthe generalprinciple provided in paragraph BC2 of ASU 2015-09. Accordingly, pleaserevise yourdisclosure toinclude additional development tables such that any additional tables do not aggregate lines with significantly different characteristics and that lines excluded fromtablesare notsubstantial.

In response to your comment, we propose to revise our disclosure, commencing with our Annual Report on Form 10-K for the year ended December 31, 2017, to include three additional development tables: general liability and umbrella - occurrence, general liability – claims made, and homeowners. With this revision, our total coverage for disclosed development tables will be approximately 93% of consolidated reserves, net of reinsurance. We believe this level of disclosure provides sufficient information that would allow users to assess the amount, timing and uncertainty of cash flows arising from insurance contracts. None of the remaining product lines excluded from the tables would be substantial and none would represent more than 2% of total net reserves.

The following highlighted information in the attachment is proposed disclosure for future filings and includes an example footnote proforma for the additional three proposed development tables.

Should you have any questions about the information provided in this response, please do not hesitate to contact me.

Sincerely,

/s/ Jeffrey M. Farber

Jeffrey M. Farber

Executive Vice President and Chief Financial Officer

/s/ Warren E. Barnes

Warren E. Barnes

Senior Vice President & Corporate Controller

Principal Accounting Officer

cc: D. Peter Brennan

       PricewaterhouseCoopers

       Judy Jones

       PricewaterhouseCoopers

       Julie H. Jones

       Ropes & Gray

       Zachary R. Blume

       Ropes & Gray

2

17. LIABILITIES FOR OUTSTANDING CLAIMS, LOSSES AND LOSS ADJUSTMENT EXPENSES

Carried Reserves

The table below summarizes the gross, ceded and net reserve for losses and LAE and reconciles to the incurred claims development in the following section. Accordingly, the commercial multiple peril, workers’ compensation, commercial automobile liability lines and general liability and umbrella - occurrence presentation includes AIX program business. Chaucer is presented in two components, its ongoing core lines and it’s reinsured and run-off lines.

YEAR ENDED DECEMBER 31,	2016							2015
(in millions)	Gross		Ceded			Net		Gross		Ceded			Net
Commercial multiple peril	$	978.0	$	(82.1	)	$	895.9	$	813.1	$	(59.2	)	$	753.9
Workers’ compensation		715.5		(171.4	)		544.1		713.1		(178.0	)		535.1
Commercial automobile liability		431.7		(27.2	)		404.5		390.3		(28.4	)		361.9
General liability and umbrella - occurrence		466.3		(108.1	)		358.2		374.0		(88.6	)		285.4
General liability - claims made		211.1		(14.2	)		196.9		167.4		(26.8	)		140.6
Other lines		303.4		(73.3	)		230.1		216.3		(43.8	)		172.5
Total Commercial Lines and other		3,106.0		(476.3	)		2,629.7		2,674.2		(424.8	)		2,249.4
Personal automobile liability		1,416.8		(865.6	)		551.2		1,395.0		(863.5	)		531.5
Homeowners		111.1		(5.8	)		105.3		108.4		(5.3	)		103.0
Other personal lines		26.1		(1.5	)		24.6		24.3		(1.7	)		22.7
Total Personal Lines		1,554.0		(872.9	)		681.1		1,527.7		(870.5	)		657.2
Chaucer core lines		1,832.4		(552.5	)		1,279.9		1,767.6		(508.5	)		1,259.1
Chaucer reinsured and run-off lines		457.0		(373.1	)		83.9		604.9		(477.0	)		127.9
Total Chaucer		2,289.4		(925.6	)		1,363.8		2,372.5		(985.5	)		1,387.0
Total loss and LAE reserves	$	6,949.4	$	(2,274.8	)	$	4,674.6	$	6,574.4	$	(2,280.8	)	$	4,293.6

General liability and umbrella - occurrence is primarily comprised of our commercial monoline general liability and umbrella coverages. General liability - claims made is primarily comprised of our commercial professional and management liability lines. Within total Commercial Lines and other, other lines is primarily comprised of marine, voluntary pools, surety, fidelity and healthcare lines. Chaucer core lines includes marine and aviation, energy, property and casualty lines, primarily consisting of international liability and specialist liability coverages. Chaucer reinsured and run-off lines include financial and professional liability lines written in 2008 and prior and U.K. motor business, which was transferred through a 100 percent reinsurance contract as of June 30, 2015. Included in the above table, primarily in other lines, are $61.0 million and $57.7 million of gross asbestos and environmental reserves as of December 31, 2016 and 2015, respectively.

3

Incurred claims development tables

For the following net reserve components, commercial multiple peril, workers’ compensation, commercial automobile liability,  general liability and umbrella - occurrence, general liability - claims made, personal automobile liability, homeowners and Chaucer core lines, the Company is presenting incurred claims development tables by accident year. The commercial multiple peril, workers’ compensation, commercial automobile liability and general liability and umbrella - occurrence lines presentation includes AIX program business. In each of these tables, the Company is presenting the number of years for which claims are typically outstanding, which is consistent with the period at which substantially all of the reserve development has emerged based on past history. The tables presented below include cumulative incurred loss and allocated loss adjustment expenses (“ALAE”), cumulative paid loss and ALAE and IBNR balances at December 31, 2016. IBNR includes both incurred but not reported liabilities and expected development on reported claims. In addition, cumulative incurred claim counts are presented as of December 31, 2016 and claim duration is presented in a separate table disclosing the average annual percentage payout of incurred claims by age, net of reinsurance. Claim duration is calculated as an average of paid loss and ALAE divided by incurred loss and ALAE by elapsed year.  The incurred claims development tables presented are reconciled to the net carried reserves in the preceding table as of December 31, 2016.

For the domestic lines, incurred claim count information presented represents claim frequency by individual claimant and measures the frequency of direct claim settlements that have resulted in or are expected to result in claim payments. Claim count information is presented in a manner consistent with that used in the quarterly loss reserving process. A single claim event, particularly in automobile lines, may result in multiple individual claimants and, therefore, multiple claim counts. Incurred claim counts are comprised of outstanding claims and those that are closed with a loss payment and exclude those that are closed without a loss payment. A single claim event may result in multiple claims closed with a payment when a claim is subsequently reopened with further payment. In this case, a reopened claim payment is counted as an incremental claim settlement. Claim count information is not available for direct and assumed participations in various involuntary pools and residual market mechanisms, which represent approximately 5% or less of the total gross earned premium and gross incurred claims for the lines presented. Incurred claim counts are also not adjusted for the effect of claims ceded as part of reinsurance programs, although the incurred losses and cumulative paid losses presented in the following tables are presented net of reinsurance ceded.

For Chaucer core lines, the incurred claim count information presented represents claim frequency by individual claimant and measures the frequency of expected claim settlements that have resulted in or are expected to result in claim payments. While claim count information is only utilized in a limited portion of Chaucer’s quarterly loss reserving process, the counts in the following Chaucer table are presented in a manner consistent with those used by the actuaries. A single claim event may result in multiple individual claimants, and therefore, multiple claim counts. Incurred claim counts are comprised of outstanding claims and those that are closed with a loss payment and exclude those that are closed without payment. A single claim event may result in multiple claims closed with a payment when payments are made in multiple currencies. In this case, the payment in each currency is counted as an incremental claim count. A portion of the coverholder and assumed reinsurance business is reported as block claims, which represent multiple underlying individual claims for a particular loss event or for multiple loss events. Claim count information is not available for the underlying claims related to block claims, and block claims represent approximately 10% of gross incurred losses for Chaucer core lines. Therefore, these block claims are not included in the claim count information presented. Incurred claim counts are also not adjusted for the effects of claims ceded as part of reinsurance programs, although the incurred losses and cumulative paid losses presented in the following tables are presented net of reinsurance ceded.

4

Commercial multiple peril
(in millions)													As of
Incurred Losses and ALAE, Net of Reinsurance													December 31, 2016
YEARS ENDED DECEMBER 31,															Cumulative
															Incurred
Accident	2011		2012		2013		2014		2015						Claim
Year	Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		2016		IBNR		Count
2011	$	455.4	$	453.3	$	469.1	$	478.8	$	494.7	$	505.4	$	17.2		19,163
2012				480.0		462.8		456.2		459.7		475.6		20.5		17,054
2013						380.0		362.5		367.9		391.8		33.9		14,911
2014								443.9		439.6		464.8		62.9		16,102
2015										446.0		456.3		100.1		15,810
2016												447.1		181.7		15,512
Total											$	2,741.0
Cumulative Paid Losses and ALAE, Net of Reinsurance
YEARS ENDED DECEMBER 31,
Accident	2011		2012		2013		2014		2015
Year	Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		2016
2011	$	217.8	$	328.5	$	381.5	$	418.6	$	454.0	$	471.5
2012				175.8		307.5		350.8		389.3		424.2
2013						137.6		221.5		262.3		306.4
2014								171.7		267.8		316.0
2015										161.9		260.1
2016												140.3
Total											$	1,918.5
Total reserves for 2011 – 2016 accident years (incurred - paid)												822.5
Total reserves for 2010 and prior accident years												55.7
Unallocated loss adjustment expense												17.7
Net reserves at December 31, 2016											$	895.9

5

Workers' compensation
(in millions)																					As of
Incurred Losses and ALAE, Net of Reinsurance																					December 31, 2016
YEARS ENDED DECEMBER 31,																							Cumulative
																							Incurred
Accident	2007		2008		2009		2010		2011		2012		2013		2014		2015						Claim
Year	Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		2016		IBNR		Count
2007(1)	$	79.2	$	82.2	$	80.5	$	78.6	$	77.3	$	76.5	$	75.6	$	75.8	$	75.1	$	74.9	$	1.3		7,591
2008(1)				88.9		93.9		88.0		81.5		81.5		80.6		79.8		80.5		80.4		1.6		8,930
2009						93.8		87.6		82.5		80.3		79.4		79.2		77.5		77.5		1.2		8,014
2010								115.5		116.9		115.8		115.9		116.3		114.9		114.7		2.6		10,152
2011										141.4		144.2		144.3		145.5		143.8		146.7		7.5		12,428
2012												176.3		171.1		165.2		157.2		162.9		12.6		12,983
2013														179.3		167.4		160.1		154.4		15.6		11,612
2014																182.1		172.9		154.7		22.3		10,748
2015																		189.6		164.2		38.2		11,158
2016																				189.6		75.1		14,103
Total																			$	1,320.0
Cumulative Paid Losses and ALAE, Net of Reinsurance
YEARS ENDED DECEMBER 31,
Accident	2007		2008		2009		2010		2011		2012		2013		2014		2015
Year	Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		2016
2007(1)	$	15.1	$	34.9	$	46.5	$	54.4	$	59.6	$	62.0	$	63.9	$	65.5	$	66.5	$	67.3
2008(1)				17.9		40.2		52.9		60.8		64.8		67.1		69.8		71.0		72.4
2009						19.2		41.2		54.6		61.6		65.4		68.6		69.8		70.8
2010								22.1		57.2		76.9		89.5		96.5		101.0		104.2
2011										30.0		71.3		97.3		114.0		122.9		128.0
2012												30.4		74.8		102.6		120.1		130.7
2013														30.9		74.6		101.2		114.0
2014																30.6		70.5		92.3
2015																		28.0		65.7
2016																				33.9
Total																			$	879.3
Total reserves for 2007 – 2016 accident years (incurred - paid)																				440.7
Total reserves for 2006 and prior accident years																				87.5
Unallocated loss adjustment expense and other																				15.9
Net reserves at December 31, 2016																			$	544.1

(1) The incurred and cumulative paid losses and ALAE, IBNR and incurred claim counts retroactively include AIX business for all periods presented, including those periods that pre-date the acquisition of AIX on November 30, 2008.

6

Commercial automobile liability
(in millions)													As of
Incurred Losses and ALAE, Net of Reinsurance													December 31, 2016
YEARS ENDED DECEMBER 31,															Cumulative
															Incurred
Accident	2011		2012		2013		2014		2015						Claim
Year	Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		2016		IBNR		Count
2011	$	120.4	$	142.1	$	148.0	$	162.8	$	177.0	$	179.6	$	2.4		15,457
2012				166.8		167.5		173.7		189.9		198.0		5.7		14,786
2013						177.7		179.4		205.3		227.5		16.7		15,309
2014								168.5		163.3		177.3		28.7		13,464
2015										163.4		168.3		51.0		12,723
2016												157.0		87.6		10,748
Total											$	1,107.7
Cumulative Paid Losses and ALAE, Net of Reinsurance
YEARS ENDED DECEMBER 31,
Accident	2011		2012		2013		2014		2015
Year	Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		2016
2011	$	27.7	$	64.7	$	102.4	$	135.5	$	160.5	$	170.2
2012				33.3		77.0		117.0		156.9		176.3
2013						35.9		89.6		137.6		176.3
2014								33.1		70.8		102.7
2015										32.2		63.8
2016												27.8
Total											$	717.1
Total reserves for 2011 – 2016 accident years (incurred - paid)												390.6
Total reserves for 2010 and prior accident years												9.6
Unallocated loss adjustment expense												4.3
Net reserves at December 31, 2016											$	404.5

7

General liability and umbrella - occurrence
(in millions)										As of
Incurred Losses and ALAE, Net of Reinsurance										December 31, 2016
YEARS ENDED DECEMBER 31,											Cumulative
											Incurred
Accident	2009	2010	2011	2012	2013	2014	2015				Claim
Year	Unaudited	Unaudited	Unaudited	Unaudited	Unaudited	Unaudited	Unaudited	2016		IBNR	Count
2009	$ X	$ X	$ X	$ X	$ X	$X	$ X	$ X		$ X	X
2010		X	X	X	X	X	X	X		X	X
2011			X	X	X	X	X	X		X	X
2012				X	X	X	X	X		X	X
2013					X	X	X	X		X	X
2014						X	X	X		X	X
2015							X	X		X	X
2016								X		X	X
Total								$ X
Cumulative Paid Losses and ALAE, Net of Reinsurance
YEARS ENDED DECEMBER 31,
Accident	2009	2010	2011	2012	2013	2014	2015
Year	Unaudited	Unaudited	Unaudited	Unaudited	Unaudited	Unaudited	Unaudited	2016
2009	$ X	$ X	$ X	$ X	$ X	$ X	$ X	$ X
2010		X	X	X	X	X	X	X
2011			X	X	X	X	X	X
2012				X	X	X	X	X
2013					X	X	X	X
2014						X	X	X
2015							X	X
2016								X
Total								$ X
Total reserves for 2009 – 2016 accident years (incurred - paid)								X
Total reserves for 2008 and prior accident years								X
Unallocated loss adjustment expense and other								X
Net reserves at December 31, 2016								$	358.2

8

General liability - claims made
(in millions)							As of
Incurred Losses and ALAE, Net of Reinsurance							December 31, 2016
YEARS ENDED DECEMBER 31,								Cumulative
								Incurred
Accident	2012	2013	2014	2015				Claim
Year	Unaudited	Unaudited	Unaudited	Unaudited	2016		IBNR	Count
2012	$ X	$ X	$ X	$ X	$ X		$ X	X
2013		X	X	X	X		X	X
2014			X	X	X		X	X
2015				X	X		X	X
2016					X		X	X
Total					$ X
Cumulative Paid Losses and ALAE, Net of Reinsurance
YEARS ENDED DECEMBER 31,
Accident	2012	2013	2014	2015
Year	Unaudited	Unaudited	Unaudited	Unaudited	2016
2012	$ X	$ X	$ X	$ X	$ X
2013		X	X	X	X
2014			X	X	X
2015				X	X
2016					X
Total					$ X
Total reserves for 2012 – 2016 accident years (incurred - paid)					X
Total reserves for 2011 and prior accident years					X
Unallocated loss adjustment expense					X
Net reserves at December 31, 2016					$	196.9

9

Personal automobile liability
(in millions)											As of
Incurred Losses and ALAE, Net of Reinsurance											December 31, 2016
YEARS ENDED DECEMBER 31,													Cumulative
													Incurred
Accident	2012		2013		2014		2015						Claim
Year	Unaudited		Unaudited		Unaudited		Unaudited		2016		IBNR		Count
2012	$	358.4	$	366.9	$	366.3	$	376.5	$	379.8	$	5.7		51,700
2013				348.2		339.6		338.3		343.0		6.5		49,278
2014						323.1		304.1		308.8		15.1		43,268
2015								327.4		334.1		40.5		41,989
2016										337.9		109.7		39,477
Total									$	1,703.6
Cumulative Paid Losses and ALAE, Net of Reinsurance
YEARS ENDED DECEMBER 31,
Accident	2012		2013		2014		2015
Year	Unaudited		Unaudited		Unaudited		Unaudited		2016
2012	$	126.6	$	234.6	$	305.1	$	342.2	$	361.8
2013				115.3		210.5		273.3		310.1
2014						107.2		188.6		241.1
2015								112.9		205.4
2016										112.8
Total									$	1,231.2
Total reserves for 2012 – 2016 accident years (incurred - paid)										472.4
Total reserves for 2011 and prior accident years										66.5
Unallocated loss adjustment expense										12.3
Net reserves at December 31, 2016									$	551.2

10

Homeowners
(in millions)					As of
Incurred Losses and ALAE, Net of Reinsurance					December 31, 2016
YEARS ENDED DECEMBER 31,						Cumulative
						Incurred
Accident	2014	2015				Claim
Year	Unaudited	Unaudited	2016		IBNR	Count
2014	$ X	$ X	$ X		$ X	X
2015		X	X		X	X
2016			X		X	X
Total			$ X
Cumulative Paid Losses and ALAE, Net of Reinsurance
YEARS ENDED DECEMBER 31,
Accident	2014	2015
Year	Unaudited	Unaudited	2016
2014	$ X	$ X	$ X
2015		X	X
2016			X
Total			$ X
Total reserves for 2014 – 2016 accident years (incurred - paid)			X
Total reserves for 2013 and prior accident years			X
Unallocated loss adjustment expense			X
Net reserves at December 31, 2016			$	105.3

11

Chaucer core lines
(in millions)													As of
Incurred Losses and ALAE, Net of Reinsurance (1)													December 31, 2016
YEARS ENDED DECEMBER 31,															Cumulative
															Incurred
Accident	2011		2012		2013		2014		2015						Claim
Year	Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		2016		IBNR		Count
2011(2)	$	640.9	$	597.7	$	605.3	$	586.0	$	586.2	$	575.7	$	33.4		6,940
2012				420.5		337.2		342.4		325.0		318.0		31.5		5,690
2013						418.2		381.8		369.4		360.1		54.0		5,618
2014								457.7		391.6		397.1		80.4		6,934
2015										488.4		410.5		136.8		7,216
2016												505.2		329.9		4,404
Total											$	2,566.6
Cumulative Paid Losses and ALAE, Net of Reinsurance (1)
YEARS ENDED DECEMBER 31,
Accident	2011		2012		2013		2014		2015
Year	Unaudited		Unaudited		Unaudited		Unaudited		Unaudited		2016
2011(2)	$	134.2	$	296.3	$	391.0	$	438.6	$	489.3	$	513.2
2012				55.4		144.7		200.0		228.7		246.7
2013						58.2		158.4		228.4		257.5
2014								52.0		162.2		227.8
2015										52.5		146.8
2016												79.1
Total											$	1,471.1
Total reserves for 2011 – 2016 accident years (incurred - paid)												1,095.5
Total reserves for 2010 and prior accident years												129.5
Reserves for nuclear energy classes												31.8
Unallocated loss adjustment expense and other												23.1
Net reserves at December 31, 2016											$	1,279.9

(1) Chaucer incurred losses and ALAE and paid losses and ALAE that are denominated in foreign currencies are converted to U.S. dollars as of December 31, 2016, the most recent balance sheet date, for all years presented.

(2) The incurred and cumulative paid losses and ALAE, IBNR and reported claim counts retroactively includes the 6 month period that pre-dates the acquisition of Chaucer on July 1, 2011. Additionally, during 2011 Chaucer experienced an elevated level of high severity catastrophe events. For example, three such events, the February 2011 New Zealand earthquake, March 2011 Japanese tsunami and October 2011 Thailand floods totaled approximately $125 million of incurred losses, and each event was in excess of $30 million. Chaucer experienced no catastrophe events in excess of $30 million from 2012 through 2016.

12

The following table is information about average historical claims duration as of December 31, 2016. The table is computed based on the paid and incurred claims data, net of reinsurance, for the accident years presented in the preceding claims development tables.

Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance:
Unaudited
	1		2		3		4		5		6		7		8		9		10
Commercial multiple peril		36.5%		22.6%		10.1%		8.9%		7.2%		3.5%
Workers' compensation		20.0%		27.3%		16.5%		10.1%		5.9%		3.5%		2.6%		1.6%		1.6%		1.0%
Commercial automobile liability		17.3%		21.3%		20.1%		18.5%		11.9%		5.4%
GL and umbrella - occurrence	X%		X%		X%		X%		X%		X%		X%		X%
General liability - claims made	X%		X%		X%		X%		X%
Personal automobile liability		33.8%		27.6%		17.9%		10.3%		5.2%
Homeowners	X%		X%		X%
Chaucer core lines		16.4%		27.0%		17.5%		8.4%		7.2%		4.1%

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