Primary Objective: To compare the antidepressant efficacy and safety of subjects receiving DVS-233 SR versus subjects receiving placebo. Secondary Objective: To assess the response of subjects receiving DVS-233 SR for the clinical global evaluation, functionality, general wellbeing, pain, and absence of symptoms (Hamilton Psychiatric Rating Scale for Depression, 17-item \[HAM-D17\] less than or equal to 7) versus those subjects receiving placebo.
Inclusion Criteria: * Outpatients * Sexually active women participating in the study must use a medically acceptable form of contraception * Subjects must have a primary diagnosis of major depressive disorder of 4 on Clinical Global Impressions-Severity scale (CGI-S) Exclusion Criteria: * Treatment with DVS-233 SR at any time in the past * Treatment with venlafaxine (immediate release \[IR\] or extended release \[ER\]) within 90 days of study day 1 * Known hypersensitivity to venlafaxine (IR or ER)