This paper reports on an unusually large increase in cohabiting couples noted between the 2009 and 2010 Annual Social and Economic Supplement (ASEC) to the Current Population Survey (CPS).  It establishes that the increase represents a true demographic change in living arrangements of couples and is not the result of any changes in data collection or processing.  It also examines the characteristics of unmarried couples in 2009 and 2010 and offer some suggestions about factors that may have contributed to this observed increase.