This study will test the effectiveness and safety of two doses of solabegron against placebo in reducing the symptoms of overactive bladder.

Inclusion Criteria:

• Overactive bladder with symptoms of urgency with urge incontinence and frequency which may be associated with nocturia but without bladder pain.
• Body mass index in the range of = 19 kg/m2 to <35 kg/m2.

Exclusion Criteria:

• Pregnant
• Of childbearing potential or willing to use specific barrier methods outlined in the protocol.
• Grade III/IV pelvic organ prolapse with or without cystocele.
• History of interstitial cystitis or bladder related pain.
• Stress incontinence or mixed incontinence where stress incontinence is the predominant component based on prior history.
• History of pelvic prolapse repair (cystocele or rectocele) or urethral diverticulectomy within six months of screening.
• Urinary incontinence due to causes other then detrusor over activity (e.g., overflow incontinence).
• Nocturnal enuresis only.
• Urinary retention, or other evidence of poor detrusor function.
• Current or history of Urinary Tract Infection.
• Diabetes insipidus.
• History of myocardial infarction, unstable angina, or Congestive heart failure.
• Chronic severe constipation.
• History of prior anti-incontinence surgery.
• History of radiation cystitis or a history of pelvic irradiation.
• Electrostimulation, biofeedback, or bladder training therapy (behavioral therapy) during the previous month prior to screening, or the intention to initiate such therapies during the study. Pessaries and implants are also excluded.
• Received any investigational product within 30 days of enrollment into the study.