Poor medication adherence is well documented for patients with severe and persistent mental illness. The State of Missouri implemented an early alert system to notify caregivers when patients fail to refill essential prescriptions in a timely manner and as an educational resource for providers on best practices for improving treatment adherence. Missouri Medicaid patients who were prescribed at least 1 of 9 orally-administered antipsychotic medications and who had at least 1 medication possession ratio (MPR) score below 0.8 were included in the adherence intervention group. Their prescribing clinicians and case managers were messaged electronically 2 times per week at the point that failure to refill the targeted prescription was identified. Notification occurred when the prescription had lapsed at 7 days, 30 days, and 45 days, and occurred in real time. In addition, MPR scores were provided monthly for the most recent 6-month period. Change in MPR scores was measured for the intervention group and for a matched control group. Trends in MPR scores were analyzed for both groups pre, during, and post intervention. In both the intervention and postintervention periods, there was a significant difference in the MPR scores between the two groups. The intervention group had a significantly greater increase in MPR score between preintervention and intervention periods. After the conclusion of the intervention, the MPR score decreased somewhat but was still higher than during the preintervention period. Results suggest that clinicians and patients need specific data about adherence in order to address the issue.