Class of 2007 Abstract / Objectives: This 12-month retrospective, naturalistic study determined medication adherence, psychiatric hospitalizations, cost of services, cost of prescriptions, and rates of polypharmacy (less than 4 versus greater than or equal to 4 concomitant psychotropic medications) for patients receiving clozapine versus quetiapine therapy for the treatment of schizophrenia in an outpatient mental health facility. Methods: The clozapine and quetiapine groups were compared for gender, age, medication adherence rates, hospitalizations, cost of care, polypharmacy, and types of concomitant psychotropic medications over 12-months. The polypharmacy groups for clozapine and quetiapine (e.g., greater than or equal to 4 psychotropic medications versus less than 4 psychotropic medications) were compared for medication adherence. Results: A total of 71 patients met the entry criteria (44 = clozapine and 27 = quetiapine). The two groups were similar for age, gender, court order, average daily dose, and hospitalization rates. The clozapine group had a higher medication adherence rate of 0.901 (e.g., 329 days supply) compared to the quetiapine group’s adherence rate of 0.723 (e.g., 264 days supply) (p=0.007). The clozapine group had higher costs for medication, labs, and other services compared to the quetiapine group, as well as total costs of services (p=0.004). The clozapine group was on fewer concomitant psychotropic medications compared to the quetiapine group based on the rates of polypharmacy. Conclusions: Patient on clozapine therapy had improved medication adherence and lower rates of polypharmacy, but higher costs of care compared to quetiapine. The frequent monitoring required with clozapine may result in medication adherence that results in improved efficacy, less polypharmacy, and lower hospitalization rates. Further studies in larger populations are needed to compare different frequency rates of monitoring patients on outcome measures over a longer period of treatment.