The investigators wish to study acute efficacy for 12 weeks on a double blind basis and continued response after open-label treatment at week 24 follow-up. It is important to establish the acute (12 week) efficacy of desvenlafaxine in non-major chronic depression. Also, given that non-major chronic depression is by definition chronic, it is important to demonstrate that benefit persists at follow-up assessment (24 weeks); this is clinically important in trying to alleviate the significant psychosocial morbidity associated with this disorder.