We describe an animated, conversational computer agent designed to promote antipsychotic medication adherence among patients with schizophrenia. In addition to medication adherence, the agent also promotes physical activity and system usage, and includes verbal and nonverbal behavior designed to foster a therapeutic alliance with patients. We discuss special considerations in designing interventions for this patient population, and challenges in developing and evaluating conversational agents in the mental health domain. Results from a pilot evaluation study of the agent indicate that it is accepted and effective.