<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Version>2.4.0.8</Version><ReportLongName>060200 - Disclosure - Summary of Significant Accounting Policies</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

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</LabelSeparator><Level>1</Level><ElementName>us-gaap_AccountingPoliciesAbstract</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Summary of Significant Accounting Policies [Abstract]</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>us-gaap_SignificantAccountingPoliciesTextBlock</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>verboseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="c20130101to20130630" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;div style="font-family: 'Times New Roman', Times, serif; font-size: 10pt;"&gt;&lt;div style="text-align: left; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; font-weight: bold; margin-right: 0pt;"&gt;2. Summary of Significant Accounting Policies&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;These consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (&amp;#8220;U.S. GAAP&amp;#8221;) and all amounts are stated in U.S. dollars. The preparation of these consolidated financial statements requires the Manager to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates.&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: left; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; font-weight: bold; margin-right: 0pt;"&gt;Principles of Consolidation&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;The Fund owns 100% of GAI&amp;#8217;s Blended Strategies Portfolio and as such these consolidated financial statements include all the accounts of the Fund and GAI&amp;#8217;s Blended Strategies Portfolio. Intercompany transactions and balances have been eliminated in consolidation. Creditors of the Fund have recourse to all assets of the Fund for amounts due to them, while creditors of GAI would have recourse only to the assets of GAI.&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; font-weight: bold; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; font-weight: bold; margin-right: 0pt;"&gt;Investment in Graham Alternative Investment Trading LLC&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;The Fund records its investment in GAIT at fair value based upon the Fund&amp;#8217;s proportionate share of GAIT&amp;#8217;s reported net asset value in accordance with U.S. GAAP. In determining its net asset value, GAIT records its investments in Master Funds at fair value based upon GAIT&amp;#8217;s proportionate share of the Master Funds&amp;#8217; reported net asset value. The Fund records its proportionate share of GAIT&amp;#8217;s investment income and loss, expenses, fees, and realized and unrealized gains and losses on a monthly basis and includes them in the statements of operations. Purchases and sales of units in GAIT are recorded on a trade date basis. The accounting policies of GAIT are described in its attached financial statements.&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;GAIT charges its investors, including the Fund, an advisory fee, administrator&amp;#8217;s fee, brokerage fee (for 2012 periods only), sponsor fee and incentive allocation, all of which are described in detail in Note 4. The Fund does not charge any additional fees; however each investor in the Fund indirectly bears a portion of the advisory fee, brokerage fee, sponsor fee and incentive allocation charged by GAIT.&lt;/div&gt;&lt;div style="text-indent: 0pt; display: block;"&gt;&lt;br /&gt;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;At June 30, 2013 and December 31, 2012, the Fund owned 41.96% and 35.41%, respectively of GAIT.&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; font-weight: bold; margin-right: 0pt;"&gt;Fair Value&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;The fair value of the assets and liabilities of the Fund and GAIT, which qualify as financial instruments under U.S. GAAP, approximates the carrying amounts presented in the consolidated statements of financial condition. Changes in these carrying amounts are included in the consolidated statements of operations.&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;The Fund follows U.S. GAAP for fair value measurements, which defines fair value, establishes a framework for measuring fair value, and requires certain disclosures about fair value measurements. U.S. GAAP uses a three-level hierarchy for fair value measurement based on the activeness of the market and the transparency and independence of inputs used in the valuation of an asset or liability as of the measurement date.&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;The fair value hierarchy categorizes asset and liability positions into one of three levels, as summarized below, based on the inputs and assumptions used in deriving fair value.&lt;/div&gt;&lt;div style="text-indent: 0pt; display: block;"&gt;&lt;br /&gt;&lt;/div&gt;&lt;div&gt;&lt;table align="center" border="0" cellpadding="0" cellspacing="0" style="width: 100%; font-family: times new roman; font-size: 10pt;"&gt;&lt;tr valign="top"&gt;&lt;td style="width: 18pt;"&gt;&lt;div style="display: inline; font-family: Times New Roman; font-size: 10pt;"&gt;&lt;/div&gt;&lt;/td&gt;&lt;td style="width: 18pt;"&gt;&lt;div style="text-indent: 0pt; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;&amp;#183;&lt;/div&gt;&lt;/td&gt;&lt;td&gt;&lt;div style="text-align: justify; font-family: Times New Roman; font-size: 10pt;"&gt;Level 1 inputs are unadjusted closing or settlement prices for such assets or liabilities as published by the primary exchange upon which they are traded.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;&lt;/div&gt;&lt;div&gt;&lt;table align="center" border="0" cellpadding="0" cellspacing="0" style="width: 100%; font-family: times new roman; font-size: 10pt;"&gt;&lt;tr valign="top"&gt;&lt;td style="width: 18pt;"&gt;&lt;div style="display: inline; font-family: Times New Roman; font-size: 10pt;"&gt;&lt;/div&gt;&lt;/td&gt;&lt;td style="width: 18pt;"&gt;&lt;div style="text-indent: 0pt; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;&amp;#183;&lt;/div&gt;&lt;/td&gt;&lt;td&gt;&lt;div style="text-align: justify; font-family: Times New Roman; font-size: 10pt;"&gt;Level 2 inputs include quoted prices for similar assets and liabilities obtained from independent brokers and/or market makers in each security. With respect to the Fund&amp;#8217;s investment in GAIT, Level 2 inputs include the net asset value of the underlying fund in which it holds an investment.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;&lt;/div&gt;&lt;div&gt;&lt;table align="center" border="0" cellpadding="0" cellspacing="0" style="width: 100%; font-family: times new roman; font-size: 10pt;"&gt;&lt;tr valign="top"&gt;&lt;td style="width: 18pt;"&gt;&lt;div style="display: inline; font-family: Times New Roman; font-size: 10pt;"&gt;&lt;/div&gt;&lt;/td&gt;&lt;td style="width: 18pt;"&gt;&lt;div style="text-indent: 0pt; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;&amp;#183;&lt;/div&gt;&lt;/td&gt;&lt;td&gt;&lt;div style="text-align: justify; font-family: Times New Roman; font-size: 10pt;"&gt;Level 3 inputs are those which are considered unobservable and are significant in arriving at fair value.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;&lt;/div&gt;&lt;div style="text-indent: 0pt; display: block;"&gt;&lt;br /&gt;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;The Fund reports the fair value of its investment related assets and liabilities in accordance with the hierarchy established under U.S. GAAP. In accordance with this hierarchy, the Fund&amp;#8217;s investment in GAIT has been classified as a Level 2 valuation. There were no Level 3 assets or liabilities held at any point during the six month period ended June 30, 2013 or the twelve month period ended December 31, 2012 by the Fund, GAIT, or the Master Funds, and there were no transfers between levels during those periods. Transfers between levels, if any, are recognized on the actual date of the event or change in circumstances that cause the transfer.&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: left; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; font-weight: bold; margin-right: 0pt;"&gt;Indemnifications&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;&lt;div style="text-align: justify; text-indent: 0pt; display: block; font-family: Times New Roman; margin-left: 0pt; font-size: 10pt; margin-right: 0pt;"&gt;In the normal course of business, the Fund, GAIT, Graham Cash Assets LLC (&amp;#8220;Cash Assets&amp;#8221;), and the Master Funds enter into contracts that contain a variety of indemnifications. Such contracts may include those by Cash Assets and the Master Funds with their brokers and trading counterparties. The Fund&amp;#8217;s maximum exposure under these arrangements is unknown; however, the Fund has not had prior claims or losses with respect to such indemnifications and considers the risk of loss to be remote.&lt;/div&gt;&lt;/div&gt;</NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>nonnum:textBlockItemType</ElementDataType><SimpleDataType>na</SimpleDataType><ElementDefenition>The entire disclosure for all significant accounting policies of the reporting entity.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

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