<?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>108 - Disclosure - Registration Statement</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>0001335732</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>udf_RegistrationStatementAbstract</ElementName><ElementPrefix>udf_</ElementPrefix><IsBaseElement>false</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>Registration Statement [Abstract]</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>udf_RegistrationStatementTextBlock</ElementName><ElementPrefix>udf_</ElementPrefix><IsBaseElement>false</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;FONT-SIZE: 10pt;MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif "&gt;  &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  &lt;b&gt;C. Registration Statement&lt;/b&gt;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-INDENT: 0.5in; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"   align="justify"&gt;On May 15, 2006, the Offering pursuant to a  Registration Statement on Form S-11 (File No. 333-127891) was  declared effective under the Securities Act of 1933, as amended.  The Offering, at the time of such effectiveness, covered up to  &lt;font style=" FONT-SIZE: 10pt"&gt;12,500,000&lt;/font&gt; units of limited  partnership interest at a price of $&lt;font style=" FONT-SIZE: 10pt"&gt;20.00&lt;/font&gt; per unit (the &amp;#8220;Primary  Offering&amp;#8221;) and up to &lt;font style=" FONT-SIZE: 10pt"&gt;  5,000,000&lt;/font&gt; units of limited partnership interest to be issued  pursuant to our distribution reinvestment plan (the  &amp;#8220;DRIP&amp;#8221;) at a price of $&lt;font style=" FONT-SIZE: 10pt"&gt;&lt;font style=" FONT-SIZE: 10pt"&gt;20.00&lt;/font&gt;&lt;/font&gt; per unit. We had the right  to reallocate the units of limited partnership interest we were  offering between the Primary Offering and our DRIP, and pursuant to  Supplement No. 8 to our prospectus regarding the Offering, which  was filed with the Securities and Exchange Commission on September  4, 2008, we reallocated the units being offered such that &lt;font  style=" FONT-SIZE: 10pt"&gt;16,250,000&lt;/font&gt; units were offered  pursuant to the Primary Offering and &lt;font style=" FONT-SIZE: 10pt"&gt;1,250,000&lt;/font&gt; units were offered pursuant to  the DRIP. Pursuant to Supplement No. 11 to our prospectus regarding  the Offering, which was filed with the Securities and Exchange  Commission on March 6, 2009, we further reallocated the units being  offered such that &lt;font style=" FONT-SIZE: 10pt"&gt;16,500,000&lt;/font&gt;  units were offered pursuant to the Primary Offering and &lt;font  style=" FONT-SIZE: 10pt"&gt;1,000,000&lt;/font&gt; units were offered  pursuant to the DRIP. The Primary Offering &lt;font style="COLOR: black"&gt;was terminated on April 23, 2009. We extended the  offering of our units of limited partnership interest pursuant to  our DRIP until the earlier of the sale of all units of limited  partnership interest being offered pursuant to our DRIP or May 15,  2010; provided, however, that our general partner was permitted to  terminate the offering of units pursuant to our DRIP at any earlier  time.&lt;/font&gt;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-INDENT: 0.5in; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"   align="justify"&gt;On June 12, 2009, we registered &lt;font style=" FONT-SIZE: 10pt"&gt;5,000,000&lt;/font&gt; additional units to be offered  pursuant to an Amended and Restated Distribution Reinvestment Plan  in a Registration Statement on Form S-3 (File No. 333-159939)  (&amp;#8220;Secondary DRIP&amp;#8221;). As such, we ceased offering units  under the DRIP as of July 21, 2009&amp;#160;and concurrently commenced  our offering of units pursuant to the Secondary DRIP, which is  currently ongoing.&amp;#160;&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>Description containing the number of units sold in public offering and the price per unit sold.</ElementDefenition><ElementReferences>No definition available.</ElementReferences><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Registration Statement [Text Block]</Label></Row></Rows><Footnotes /><IsEquityReport>false</IsEquityReport><ReportName>Registration Statement</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.udf.com/role/RegistrationStatement</RoleURI><NumberOfCols>1</NumberOfCols><NumberOfRows>2</NumberOfRows></InstanceReport>
