This will be a multicenter, randomized, double-blind, placebo-controlled study designed to assess the tolerability, safety, and efficacy of OPC-34712 (0.25 to 6.0 mg) for the treatment of adult subjects hospitalized with an acute relapse of schizophrenia. Aripiprazole (10 to 20 mg) is included as a positive control to confirm the assay sensitivity of the study. A total of approximately 563 subjects will be screened at an estimated 75 sites worldwide in order to obtain approximately 450 randomized subjects.