This is a multicenter, randomized, double blind, placebo controlled study of the safety and efficacy of SEP-225441 (eszopiclone) in male and female adult subjects with a diagnosis of generalized anxiety disorder (GAD). The study consists of a screening period of 7-10 days, 8 weeks of treatment, and a 7 day follow-up period. This study was previously posted by Sepracor Inc. In October 2009, Sepracor Inc. was acquired by Dainippon Sumitomo Pharma., and in October 2010, Sepracor Inc's name was changed to Sunovion Pharmaceuticals Inc.