<?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>117 - Disclosure - Income Taxes</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>2</Level><ElementName>us-gaap_IncomeTaxDisclosureTextBlock</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>terseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="eol_PE77887---1310-Q0004_STD_181_20130630_0" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;div&gt;
&lt;p style="MARGIN-TOP: 18px; MARGIN-BOTTOM: 0px"&gt;&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;&lt;b&gt;&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;&lt;b&gt;10. Income
Taxes&lt;/b&gt;&lt;/font&gt;&lt;/b&gt;&lt;/font&gt;&lt;/p&gt;
&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;
&lt;!-- xbrl,body --&gt;&lt;/font&gt;
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&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;The Company recognizes
federal, state and foreign current tax liabilities or assets based
on its estimate of taxes payable to or refundable by tax
authorities in the current fiscal year. The Company also recognizes
federal, state and foreign deferred tax liabilities or assets based
on the Company&amp;#x2019;s estimate of future tax effects attributable
to temporary differences and carry forwards. The Company records a
valuation allowance to reduce any deferred tax assets by the amount
of any tax benefits that, based on available evidence and judgment,
are not expected to be realized.&lt;/font&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="MARGIN-TOP: 12px; TEXT-INDENT: 4%; MARGIN-BOTTOM: 0px"&gt;
&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;The Company assesses
whether a valuation allowance should be recorded against its
deferred tax assets based on the consideration of all available
evidence, using a &amp;#x201C;more-likely-than-not&amp;#x201D; realization
standard. The four sources of taxable income that must be
considered in determining whether deferred tax assets will be
realized are: (1)&amp;#xA0;future reversals of existing taxable
temporary differences (i.e., offset of gross deferred tax assets
against gross deferred tax liabilities); (2)&amp;#xA0;taxable income in
prior carryback years, if carryback is permitted under the
applicable tax law; (3)&amp;#xA0;tax planning strategies and
(4)&amp;#xA0;future taxable income exclusive of reversing temporary
differences and carryforwards.&lt;/font&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="MARGIN-TOP: 12px; TEXT-INDENT: 4%; MARGIN-BOTTOM: 0px"&gt;
&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;In assessing whether a
valuation allowance is required, significant weight is to be given
to evidence that can be objectively verified. A significant factor
in the Company&amp;#x2019;s assessment is that the Company is in a
three-year historical cumulative loss position. This fact, combined
with uncertain near-term market and economic conditions, reduced
the Company&amp;#x2019;s ability to rely on projections of future
taxable income in assessing the realizability of its deferred tax
assets.&lt;/font&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="MARGIN-TOP: 12px; TEXT-INDENT: 4%; MARGIN-BOTTOM: 0px"&gt;
&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;After a review of the four
sources of taxable income as of June&amp;#xA0;30, 2013 (as described
above), the Company recognized increases in the valuation allowance
primarily related to its U.S.-based deferred tax amounts, resulting
from carryforward net operating losses generated during the three
and six months ended June&amp;#xA0;30, 2013. These deferred tax
benefits, combined with a corresponding charge to income tax
expense related to an increased valuation allowance of $4.4 million
and $8.8 million for the three and six months ended June&amp;#xA0;30,
2013, respectively, resulted in an insignificant effective income
tax rate. The Company&amp;#x2019;s valuation allowance was $72.7 million
on net deferred tax assets of $73.2 million at June&amp;#xA0;30, 2013.
The net unreserved portion of the Company&amp;#x2019;s remaining
deferred tax assets at June&amp;#xA0;30, 2013 primarily related to
research and development tax credits associated with the
Company&amp;#x2019;s Canadian subsidiary.&lt;/font&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="MARGIN-TOP: 12px; TEXT-INDENT: 4%; MARGIN-BOTTOM: 0px"&gt;
&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;For the three and six
months ended June&amp;#xA0;30, 2013, the Company recorded an income tax
expense, including discrete items, of $104,000 and expense of
$21,000, respectively. These amounts vary from the income tax
benefit that would be computed at the U.S. statutory rate resulting
from its operating loss during those same periods primarily due to
the aforementioned offsetting increase in the Company&amp;#x2019;s
deferred tax assets valuation allowance.&lt;/font&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="MARGIN-TOP: 12px; TEXT-INDENT: 4%; MARGIN-BOTTOM: 0px"&gt;
&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;The Company follows the
accounting guidance related to financial statement recognition,
measurement and disclosure of uncertain tax positions. The Company
recognizes the impact of an uncertain income tax position on an
income tax return at the largest amount that is
&amp;#x201C;more-likely-than-not&amp;#x201D; to be sustained upon audit by
the relevant taxing authority. An uncertain income tax position
will not be recognized if it has less than a 50% likelihood of
being sustained. As of June&amp;#xA0;30, 2013 and December&amp;#xA0;31,
2012, the total liability for unrecognized tax benefits was
$199,000 and $367,000, respectively, and is included in other
long-term liabilities.&amp;#xA0;For the three and six months ended
June&amp;#xA0;30, 2013, the Company included $1,000 of interest expense
and $168,000 of interest benefit, respectively, related to
uncertain tax positions in its condensed consolidated statements of
operations.&lt;/font&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="MARGIN-TOP: 12px; TEXT-INDENT: 4%; MARGIN-BOTTOM: 0px"&gt;
&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;In the fourth quarter of
2013, the Company expects to release $71,000 of its liability for
unrecognized tax benefits due to the expiration of the statute of
limitations applicable to the 2008 taxable year.&lt;/font&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="MARGIN-TOP: 12px; MARGIN-BOTTOM: 0px; FONT-SIZE: 1px"&gt;
&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;&amp;#xA0;&lt;/font&gt;&lt;/p&gt;
&lt;p style="MARGIN-TOP: 0px; TEXT-INDENT: 4%; MARGIN-BOTTOM: 0px"&gt;
&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;The Company and its
subsidiaries file U.S., state, and foreign income tax returns in
jurisdictions with various statutes of limitations. The California
Franchise Tax Board is currently conducting an examination of the
Company&amp;#x2019;s California income tax returns for 2006 and
2007.&amp;#xA0;The Company is also subject to various Federal income
tax examinations for the 2003 through 2010 calendar years due to
the availability of net operating loss carryforwards. The Company
believes appropriate provisions for all outstanding issues have
been made for all jurisdictions and all open years. However,
because audit outcomes and the timing of audit settlements are
subject to significant uncertainty, the Company&amp;#x2019;s current
estimate of the total amounts of unrecognized tax benefits could
increase or decrease for all open years.&lt;/font&gt;&lt;/font&gt;&lt;/p&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 income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

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