Abstract: Virtual Standardized Patients (VSPs) are computer-based training simulations that expand access to experiential, evidence-based mental health training at low cost and scale. This paper presents three phases of user-centered design studies to develop a VSP for Safety Planning Intervention (SPI) in the Department of Veterans Affairs (VA) and Department of Defense (DoD). VA and DoD mental health staff, trainees, and subject matter experts participated in qualitative interviews, prototype usability testing, and beta testing. Results identified key design features for effective training. Usability ratings of the prototype and beta were good, with higher ratings among trainees. Critical improvements were made to performance feedback, and users helped refine dialog clarity and training tasks. The resulting SPI VSP is now poised for a pilot randomized trial to evaluate training outcomes relative to routine training. If effective, it may provide a scalable, cost-effective way to improve dissemination of a promising suicide prevention intervention.