<?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>114 - Disclosure - Restructuring Activities</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>eol_PE2365----1310-Q0008_STD_181_20130630_0</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0000913142</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>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>4</Level><ElementName>us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock</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_PE2365----1310-Q0008_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;Note 7: Restructuring
Activities&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" 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, we recorded severance and other
restructuring costs of $5.0 million and $5.8 million, respectively.
The majority of these costs were recorded in our Broadcast segment,
which recognized $3.5 million and $4.3 million of severance and
other restructuring costs for the three and six months ended
June&amp;#xA0;30, 2013, respectively. The other restructuring costs
included relocation, equipment transfer, and other costs. The
Broadcast segment also recorded $2.7 million of accelerated
depreciation expense for both the three and six months ended
June&amp;#xA0;30, 2013. These costs were incurred primarily as a result
of facility consolidation in New York for recently acquired
locations and other acquisition integration activities. The
Industrial IT segment also recognized $1.3 million of severance
expense for both the three and six months ended June&amp;#xA0;30,
2013.&lt;/font&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="MARGIN-TOP: 12px; 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;Of the total severance and
other restructuring costs recognized for the three months ended
June&amp;#xA0;30, 2013, $3.1 million, $1.0 million, and $0.9 million
were included in cost of sales, selling, general and administrative
expenses, and research and development, respectively. Of the total
severance and other restructuring costs recognized for the six
months ended June&amp;#xA0;30, 2013, $3.2 million, $1.6 million, and
$1.0 million were included in cost of sales, selling, general and
administrative expenses, and research and development,
respectively. We expect the majority of the costs related to these
actions will be paid in 2013.&lt;/font&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="MARGIN-TOP: 12px; 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;We expect to incur
additional severance and other restructuring costs and accelerated
depreciation expense in 2013 of approximately $11 million as a
result of the Broadcast activities discussed above. We continue to
review our business strategies and evaluate potential new
restructuring actions. This could result in additional
restructuring costs in future periods.&lt;/font&gt;&lt;/font&gt;&lt;/p&gt;
&lt;font style="FONT-FAMILY: Times New Roman" size="2"&gt;
&lt;!-- xbrl,n --&gt;&lt;/font&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 restructuring and related activities. Description of restructuring activities such as exit and disposal activities, include facts and circumstances leading to the plan, the expected plan completion date, the major types of costs associated with the plan activities, total expected costs, the accrual balance at the end of the period, and the periods over which the remaining accrual will be settled.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 420

 -SubTopic 10

 -Section S99

 -Paragraph 1

 -Subparagraph (SAB TOPIC 5.P.3)

 -URI http://asc.fasb.org/extlink&amp;oid=27011515&amp;loc=d3e140864-122747



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

 -Publisher SEC

 -Name Staff Accounting Bulletin (SAB)

 -Number Topic 5

 -Section P

 -Subsection 3, 4



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

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 420

 -SubTopic 10

 -Section S99

 -Paragraph 2

 -Subparagraph (SAB TOPIC 5.P.4)

 -URI http://asc.fasb.org/extlink&amp;oid=27011515&amp;loc=d3e140904-122747



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

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 420

 -SubTopic 10

 -Section 50

 -Paragraph 1

 -URI http://asc.fasb.org/extlink&amp;oid=6394359&amp;loc=d3e17939-110869



</ElementReferences><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Restructuring Activities</Label></Row></Rows><Footnotes /><IsEquityReport>false</IsEquityReport><ReportName>Restructuring Activities</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.belden.com/taxonomy/role/NotesToFinancialStatementsRestructuringAndRelatedActivitiesDisclosureTextBlock</RoleURI><NumberOfCols>1</NumberOfCols><NumberOfRows>1</NumberOfRows></InstanceReport>
