<?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>106 - Disclosure - Basis of Presentation and Principles of Consolidation</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><CurrencyCode /><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName /><CurrencySymbol /><contextRef><ContextID>P01_01_2013To06_30_2013</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0001356949</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2013-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2013-06-30T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS /><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol /><Labels><Label Key="CalendarSupplement" Id="0" Label="6 Months Ended" /><Label Key="Calendar" Id="1" Label="Jun. 30, 2013" /></Labels></Column></Columns><Rows><Row FlagID="0"><Id>1</Id><IsAbstractGroupTitle>true</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>1</Level><ElementName>us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract</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>Organization, Consolidation and Presentation Of Financial Statements [Abstract]</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock</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="P01_01_2013To06_30_2013" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>              &lt;div style="clear:both;FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt;MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif "&gt;  &lt;div style="clear:both;FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt;MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  &lt;b&gt;1. Basis of Presentation and Principles of  Consolidation&lt;/b&gt;&lt;/div&gt;    &lt;div style="clear:both;FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt;TEXT-INDENT: 0.5in; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both;FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt;TEXT-INDENT: 0.25in; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  Houston Wire &amp;amp; Cable Company (the &amp;#8220;Company&amp;#8221;),  through its wholly owned subsidiaries, HWC Wire &amp;amp; Cable  Company, Advantage Wire &amp;amp; Cable and Cable Management Services  Inc., provides wire and cable, hardware and related services to the  U.S. market through twenty-one locations in thirteen states  throughout the United States. The Company has no other business  activity.&lt;/div&gt;    &lt;div style="clear:both;FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt;TEXT-INDENT: 0.5in; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both;FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt;TEXT-INDENT: 0.25in; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  The consolidated financial statements as of June 30, 2013 and for  the three and six months ended June 30, 2013 and 2012 have been  prepared following accounting principles generally accepted in the  United States (&amp;#8220;GAAP&amp;#8221;) for interim financial  information and Article 10 of Regulation S-X.&amp;#160;Accordingly,  they do not include all of the information and footnotes required  by GAAP for complete financial statements.&amp;#160;In the opinion of  management, all adjustments, consisting only of normal recurring  adjustments, considered necessary for a fair presentation of the  results of these interim periods have been included.&amp;#160;The  results of operations for the interim periods are not necessarily  indicative of the results that may be expected for the full year.  All significant inter-company balances and transactions have been  eliminated. The Company has evaluated subsequent events through the  time these financial statements in this Form 10-Q were filed with  the Securities and Exchange Commission (the  &amp;#8220;SEC&amp;#8221;).&lt;/div&gt;    &lt;div style="clear:both;FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt;TEXT-INDENT: 0.5in; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both;FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt;TEXT-INDENT: 0.25in; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  The preparation of the financial statements in conformity with GAAP  requires management to make estimates and assumptions that affect  the amounts reported in the financial statements and accompanying  notes. The most significant estimates are those relating to the  allowance for doubtful accounts, the inventory obsolescence  reserve, the reserve for returns and allowances, vendor rebates and  asset impairments. Actual results could differ materially from the  estimates and assumptions used for the preparation of the financial  statements.&lt;/div&gt;    &lt;div style="clear:both;FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt;TEXT-INDENT: 0.5in; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both;FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt;TEXT-INDENT: 0.25in; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  For further information, refer to the consolidated financial  statements and footnotes thereto included in the Company&amp;#8217;s  Annual Report on Form 10-K for the fiscal year ended December 31,  2012 filed with the SEC.&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 organization, consolidation and basis of presentation of financial statements disclosure.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 810

 -SubTopic 10

 -Section 50

 -Paragraph 8

 -URI http://asc.fasb.org/extlink&amp;oid=28200181&amp;loc=SL6228881-111685



Reference 2: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 720

 -SubTopic 15

 -URI http://asc.fasb.org/subtopic&amp;trid=2122524



Reference 3: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 205

 -SubTopic 10

 -Section 50

 -Paragraph 1

 -URI http://asc.fasb.org/extlink&amp;oid=6359566&amp;loc=d3e326-107755



Reference 4: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 235

 -SubTopic 10

 -Section 50

 -Paragraph 3

 -URI http://asc.fasb.org/extlink&amp;oid=6367646&amp;loc=d3e18780-107790



Reference 5: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 205

 -SubTopic 10

 -Section 45

 -Paragraph 3

 -URI http://asc.fasb.org/extlink&amp;oid=7668296&amp;loc=d3e288-107754



Reference 6: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 810

 -SubTopic 10

 -URI http://asc.fasb.org/subtopic&amp;trid=2197480



Reference 7: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 810

 -SubTopic 10

 -Section 50

 -Paragraph 1

 -URI http://asc.fasb.org/extlink&amp;oid=18733093&amp;loc=d3e5614-111684



Reference 8: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 915

 -SubTopic 235

 -Section 50

 -Paragraph 1

 -URI http://asc.fasb.org/extlink&amp;oid=6472506&amp;loc=d3e38932-110933



Reference 9: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 852

 -SubTopic 10

 -URI http://asc.fasb.org/subtopic&amp;trid=2209116



Reference 10: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 272

 -SubTopic 10

 -Section 50

 -Paragraph 3

 -URI http://asc.fasb.org/extlink&amp;oid=6373374&amp;loc=d3e70478-108055



Reference 11: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 275

 -SubTopic 10

 -URI http://asc.fasb.org/subtopic&amp;trid=2134480



Reference 12: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 205

 -SubTopic 10

 -URI http://asc.fasb.org/subtopic&amp;trid=2122150



</ElementReferences><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Basis of Presentation and Principles of Consolidation</Label></Row></Rows><Footnotes /><IsEquityReport>false</IsEquityReport><ReportName>Basis of Presentation and Principles of Consolidation</ReportName><MonetaryRoundingLevel>UnKnown</MonetaryRoundingLevel><SharesRoundingLevel>UnKnown</SharesRoundingLevel><PerShareRoundingLevel>UnKnown</PerShareRoundingLevel><ExchangeRateRoundingLevel>UnKnown</ExchangeRateRoundingLevel><HasCustomUnits>true</HasCustomUnits><IsEmbedReport>false</IsEmbedReport><IsMultiCurrency>false</IsMultiCurrency><ReportType>Sheet</ReportType><RoleURI>http://www.houwire.com/role/BasisOfPresentationAndPrinciplesOfConsolidation</RoleURI><NumberOfCols>1</NumberOfCols><NumberOfRows>2</NumberOfRows></InstanceReport>
