The paper explores the reasons for the sharp decline in the number of same-sex spouses reported in the American Community Survey (ACS) between 2007 and 2008. Changes were made to the 2008 American Community Survey (ACS) questionnaire that reflected requests by agencies for additional questions on the survey. Modifications and improvements to existing questions also changed the format and layout of the questionnaire. In addition, technological improvements were made in the data collection and capture phase of the ACS. We believe that some of these design and processing changes may have contributed to the observed decline in the estimated number of same-sex partner households between 2007 and 2008 and suggests that the previous ACS surveys may have over-estimated the component of the total number of these households that were originally reported as same-sex spouses. This paper will provide possible explanations for this decline and examine the potential effect of these changes on overall estimates and characteris tics of same-sex couple households between 2007 and 2008.