﻿<?xml version="1.0" encoding="utf-8"?>
<InstanceReport xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>2.2.0.7</Version>
  <hasSegments>false</hasSegments>
  <ReportName>Acquisitions</ReportName>
  <ReportLongName>10201 - Disclosure - Acquisitions</ReportLongName>
  <DisplayLabelColumn>true</DisplayLabelColumn>
  <ShowElementNames>false</ShowElementNames>
  <RoundingOption />
  <HasEmbeddedReports>false</HasEmbeddedReports>
  <Columns>
    <Column>
      <LabelColumn>false</LabelColumn>
      <Id>1</Id>
      <Labels>
        <Label Id="1" Label="3 Months Ended" />
        <Label Id="2" Label="Sep. 26, 2010" />
      </Labels>
      <CurrencyCode>USD</CurrencyCode>
      <FootnoteIndexer />
      <hasSegments>false</hasSegments>
      <hasScenarios>false</hasScenarios>
      <Segments />
      <Scenarios />
      <Units>
        <Unit>
          <UnitID>Unit1</UnitID>
          <UnitType>Standard</UnitType>
          <StandardMeasure>
            <MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema>
            <MeasureValue>USD</MeasureValue>
            <MeasureNamespace>iso4217</MeasureNamespace>
          </StandardMeasure>
          <Scale>0</Scale>
        </Unit>
        <Unit>
          <UnitID>Unit12</UnitID>
          <UnitType>Standard</UnitType>
          <StandardMeasure>
            <MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema>
            <MeasureValue>shares</MeasureValue>
            <MeasureNamespace>xbrli</MeasureNamespace>
          </StandardMeasure>
          <Scale>0</Scale>
        </Unit>
        <Unit>
          <UnitID>Unit13</UnitID>
          <UnitType>Standard</UnitType>
          <StandardMeasure>
            <MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema>
            <MeasureValue>pure</MeasureValue>
            <MeasureNamespace>xbrli</MeasureNamespace>
          </StandardMeasure>
          <Scale>0</Scale>
        </Unit>
        <Unit>
          <UnitID>Unit14</UnitID>
          <UnitType>Divide</UnitType>
          <NumeratorMeasure>
            <MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema>
            <MeasureValue>USD</MeasureValue>
            <MeasureNamespace>iso4217</MeasureNamespace>
          </NumeratorMeasure>
          <DenominatorMeasure>
            <MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema>
            <MeasureValue>shares</MeasureValue>
            <MeasureNamespace>xbrli</MeasureNamespace>
          </DenominatorMeasure>
          <Scale>0</Scale>
        </Unit>
      </Units>
      <CurrencySymbol>$</CurrencySymbol>
    </Column>
  </Columns>
  <Rows>
    <Row>
      <Id>2</Id>
      <Label>Acquisitions</Label>
      <Level>0</Level>
      <ElementName>us-gaap_BusinessAcquisitionEntityAcquiredAndReasonForAcquisitionAbstract</ElementName>
      <ElementPrefix>us-gaap</ElementPrefix>
      <IsBaseElement>true</IsBaseElement>
      <BalanceType>na</BalanceType>
      <PeriodType>duration</PeriodType>
      <ShortDefinition>No definition available.</ShortDefinition>
      <IsReportTitle>false</IsReportTitle>
      <IsSegmentTitle>false</IsSegmentTitle>
      <IsSubReportEnd>false</IsSubReportEnd>
      <IsCalendarTitle>false</IsCalendarTitle>
      <IsTuple>false</IsTuple>
      <IsAbstractGroupTitle>true</IsAbstractGroupTitle>
      <IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow>
      <IsEquityAdjustmentRow>false</IsEquityAdjustmentRow>
      <IsBeginningBalance>false</IsBeginningBalance>
      <IsEndingBalance>false</IsEndingBalance>
      <IsReverseSign>false</IsReverseSign>
      <PreferredLabelRole />
      <IsEPS>false</IsEPS>
      <FootnoteIndexer />
      <Cells>
        <Cell>
          <Id>1</Id>
          <ShowCurrencySymbol>false</ShowCurrencySymbol>
          <IsNumeric>false</IsNumeric>
          <IsRatio>false</IsRatio>
          <DisplayZeroAsNone>false</DisplayZeroAsNone>
          <NumericAmount>0</NumericAmount>
          <RoundedNumericAmount>0</RoundedNumericAmount>
          <NonNumbericText />
          <NonNumericTextHeader />
          <FootnoteIndexer />
          <hasSegments>false</hasSegments>
          <hasScenarios>false</hasScenarios>
          <DisplayDateInUSFormat>false</DisplayDateInUSFormat>
        </Cell>
      </Cells>
      <OriginalInstanceReportColumns />
      <ElementDataType>xbrli:stringItemType</ElementDataType>
      <SimpleDataType>string</SimpleDataType>
      <ElementDefenition>No definition available.</ElementDefenition>
      <IsTotalLabel>false</IsTotalLabel>
    </Row>
    <Row>
      <Id>3</Id>
      <Label>Acquisitions</Label>
      <Level>1</Level>
      <ElementName>us-gaap_BusinessCombinationDisclosureTextBlock</ElementName>
      <ElementPrefix>us-gaap</ElementPrefix>
      <IsBaseElement>true</IsBaseElement>
      <BalanceType>na</BalanceType>
      <PeriodType>duration</PeriodType>
      <ShortDefinition>No definition available.</ShortDefinition>
      <IsReportTitle>false</IsReportTitle>
      <IsSegmentTitle>false</IsSegmentTitle>
      <IsSubReportEnd>false</IsSubReportEnd>
      <IsCalendarTitle>false</IsCalendarTitle>
      <IsTuple>false</IsTuple>
      <IsAbstractGroupTitle>false</IsAbstractGroupTitle>
      <IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow>
      <IsEquityAdjustmentRow>false</IsEquityAdjustmentRow>
      <IsBeginningBalance>false</IsBeginningBalance>
      <IsEndingBalance>false</IsEndingBalance>
      <IsReverseSign>false</IsReverseSign>
      <PreferredLabelRole>terselabel</PreferredLabelRole>
      <IsEPS>false</IsEPS>
      <FootnoteIndexer />
      <Cells>
        <Cell>
          <Id>1</Id>
          <ShowCurrencySymbol>false</ShowCurrencySymbol>
          <IsNumeric>false</IsNumeric>
          <IsRatio>false</IsRatio>
          <DisplayZeroAsNone>false</DisplayZeroAsNone>
          <NumericAmount>0</NumericAmount>
          <RoundedNumericAmount>0</RoundedNumericAmount>
          <NonNumbericText>&lt;div&gt; &lt;font style="font-family: Times New Roman;" class="_mt" size="2"&gt;
&lt;/font&gt;
&lt;div&gt;
&lt;p style="margin-top: 18px; margin-bottom: 0px;"&gt;&lt;font style="font-family: Times New Roman;" class="_mt" size="2"&gt;&lt;b&gt;Note 2. Acquisitions &lt;/b&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="margin-top: 6px; margin-bottom: 0px;"&gt;&lt;font style="font-family: Times New Roman;" class="_mt" size="2"&gt;&lt;b&gt;&lt;i&gt;Acquisition of LED Lighting Fixtures, Inc. &lt;/i&gt;&lt;/b&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="margin-top: 6px; margin-bottom: 0px;"&gt;&lt;font style="font-family: Times New Roman;" class="_mt" size="2"&gt;On February&amp;nbsp;29, 2008 the Company acquired LED Lighting Fixtures, Inc. ("LLF") through a wholly owned subsidiary that merged into Cree, Inc. on June&amp;nbsp;27, 2010. The Company acquired all of the outstanding share capital of LLF in exchange for total upfront consideration of $&lt;font class="_mt"&gt;80.8&lt;/font&gt; million, consisting of (1)&amp;nbsp;$&lt;font class="_mt"&gt;16.5&lt;/font&gt; million in cash, (2)&amp;nbsp;approximately 1.9&amp;nbsp;million shares of the Company's common stock valued at $&lt;font class="_mt"&gt;58.8&lt;/font&gt; million, (3)&amp;nbsp;the assumption of fully vested LLF employee stock options valued at $&lt;font class="_mt"&gt;4.5&lt;/font&gt; million, and (4)&amp;nbsp;transaction costs of $&lt;font class="_mt"&gt;1.0&lt;/font&gt; million consisting primarily of professional fees incurred relating to attorneys, accountants and valuation advisors. Under the acquisition terms, additional consideration of up to $&lt;font class="_mt"&gt;26.4&lt;/font&gt; million would become payable to the former shareholders of LLF if defined product development targets and key employee retention measures were achieved over the three calendar years following the acquisition. &lt;/font&gt;&lt;/p&gt;
&lt;p style="margin-top: 12px; margin-bottom: 0px;"&gt;&lt;font style="font-family: Times New Roman;" class="_mt" size="2"&gt;LLF met the conditions necessary for the earn-out payment for the calendar years ended December&amp;nbsp;31, 2008 and 2009 and as a result, the Company made a cash payment in the amount of $&lt;font class="_mt"&gt;4.4&lt;/font&gt; million to the former shareholders of LLF in the third quarter of fiscal 2009 and a cash payment in the amount of $&lt;font class="_mt"&gt;8.8&lt;/font&gt; million to the former shareholders of LLF in the third quarter of fiscal 2010, thus increasing goodwill in the Company's consolidated financial statements. If LLF meets the conditions necessary for the earn-out payment during the calendar year ending December&amp;nbsp;31, 2010, an additional contingent cash payment totaling up to $&lt;font class="_mt"&gt;13.2&lt;/font&gt; million would become payable to the former shareholders of LLF. If such contingent payment occurs, it will be considered as additional purchase price and result in an increase in goodwill. &lt;/font&gt;&lt;/p&gt;
&lt;p style="margin-top: 12px; margin-bottom: 0px;"&gt;&lt;font style="font-family: Times New Roman;" class="_mt" size="2"&gt;The assets, liabilities, and operating results of LLF have been included in the Company's consolidated financial statements from the date of acquisition and are reflected in all periods presented in the accompanying financial statements. &lt;/font&gt;&lt;/p&gt;
&lt;p style="margin-top: 18px; margin-bottom: 0px;"&gt;&lt;font style="font-family: Times New Roman;" class="_mt" size="2"&gt;&lt;b&gt;&lt;i&gt;Acquisition of COTCO Luminant Device Limited &lt;/i&gt;&lt;/b&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="margin-top: 6px; margin-bottom: 0px;"&gt;&lt;font style="font-family: Times New Roman;" class="_mt" size="2"&gt;On March&amp;nbsp;30, 2007, the Company acquired COTCO Luminant Device Limited, a Hong Kong company (now Cree Hong Kong Limited) ("COTCO"), from COTCO Holdings Limited, a Hong Kong company (now United Luminous International (Holdings) Limited) ("Holdings"). The Company acquired all of the outstanding share capital of COTCO in exchange for consideration consisting of approximately 7.6&amp;nbsp;million shares of the Company's common stock and $&lt;font class="_mt"&gt;77.3&lt;/font&gt; million cash. Under the acquisition terms, additional consideration would become payable to Holdings or its designees in the event COTCO achieved specific EBITDA targets over the Company's two full fiscal years following the acquisition. For fiscal 2008 results, the Company made a cash payment in the amount of $&lt;font class="_mt"&gt;60.0&lt;/font&gt; million in fiscal 2009. For fiscal 2009 results, the Company made a cash payment in the amount of $&lt;font class="_mt"&gt;57.1&lt;/font&gt; million in fiscal 2010. These incremental payments were treated as additional purchase price and resulted in an increase to goodwill in the Company's consolidated financial statements. &lt;/font&gt;&lt;/p&gt;
&lt;p style="margin-top: 12px; margin-bottom: 0px;"&gt;&lt;font style="font-family: Times New Roman;" class="_mt" size="2"&gt;The assets, liabilities, and operating results of COTCO have been included in the Company's consolidated financial statements from the date of acquisition and are reflected in all periods presented in the accompanying financial statements. &lt;/font&gt;&lt;/p&gt;&lt;/div&gt; &lt;/div&gt;</NonNumbericText>
          <NonNumericTextHeader>Note 2. Acquisitions
Acquisition of LED Lighting Fixtures, Inc.
On February&amp;nbsp;29, 2008 the Company acquired LED Lighting Fixtures, Inc. ("LLF") through a</NonNumericTextHeader>
          <FootnoteIndexer />
          <hasSegments>false</hasSegments>
          <hasScenarios>false</hasScenarios>
          <DisplayDateInUSFormat>false</DisplayDateInUSFormat>
        </Cell>
      </Cells>
      <OriginalInstanceReportColumns />
      <ElementDataType>us-types:textBlockItemType</ElementDataType>
      <SimpleDataType>textblock</SimpleDataType>
      <ElementDefenition>Description of a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. This element may be used as a single block of text to encapsulate the entire disclosure (including data and tables) regarding business combinations, including leverage buyout transactions (as applicable).</ElementDefenition>
      <ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 141
 -Paragraph 51, 52

Reference 2: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Emerging Issues Task Force (EITF)
 -Number 88-16

Reference 3: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 141R
 -Paragraph 67-73

Reference 4: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 141R
 -Paragraph F4
 -Subparagraph e
 -Appendix F

</ElementReferences>
      <IsTotalLabel>false</IsTotalLabel>
    </Row>
  </Rows>
  <Footnotes />
  <NumberOfCols>1</NumberOfCols>
  <NumberOfRows>2</NumberOfRows>
  <HasScenarios>false</HasScenarios>
  <MonetaryRoundingLevel>UnKnown</MonetaryRoundingLevel>
  <SharesRoundingLevel>UnKnown</SharesRoundingLevel>
  <PerShareRoundingLevel>UnKnown</PerShareRoundingLevel>
  <HasPureData>false</HasPureData>
  <SharesShouldBeRounded>true</SharesShouldBeRounded>
</InstanceReport>
