Purpose Previous evidence suggests psychiatric pharmacists have improved patient symptoms and provide valuable information. However, there are limited recent data regarding clinical pharmacists performing interventions in a psychiatric setting and its effects on costs. Additionally, there are no data that differentiate between psychiatric hospital staff pharmacists' (HSP), faculty clinical pharmacists' (FCP), and student pharmacists' (SP) interventions. Therefore, the objective of this study is to evaluate and describe interventions made by HSPs, FCPs, and SPs in a psychiatric hospital and cost savings. Methods A retrospective review of interventions made in a psychiatric hospital over 18 months was performed. Descriptive statistics and cost analysis were also determined through Pharmacy OneSource. Results A total of 2,220 interventions were made. Among HSPs (n = 4), there were 1,734 interventions including clarifications of orders (n = 592) and MAR discrepancies (n = 385). FCPs (n = 2) contributed 358 interventions consisting of dose recommendations/adjustments (n = 78), drug lab/level recommendations (n = 47), and therapeutic recommendations (n = 37). Additionally, SPs (n = 27) made 128 interventions including patient medication history (n = 31), drug information (n = 30), and counseling patients (n = 25). Annual cost savings were estimated at $125,500 with approximately 90% contributed by HSPs. Conclusion Pharmacy personnel contributed a considerable amount of interventions providing a cost savings to the hospital. Also, HSPs provided a greater number of interventions resulting in decreased costs. In our setting, HSPs, FCPs, and SPs contribute different clinical therapeutic interventions that may optimize patient care.