This is a multi-center, open-label, Phase II study of obatoclax administered alone as a weekly, 3-hour or 24-hour infusion for 12 weeks followed by a combination with rituximab to patients with previously-untreated Follicular Lymphoma. For purposes of clinical evaluations, treatment cycles will occur in 4-week periods. Treatment may be administered on an outpatient basis. No investigational or commercial agents or therapies other than those described may be administered with the intent to treat the patient's malignancy.