Mobile devices can be used to deliver psychosocial interventions, yet there is little prior application in severe mental illness. We provide the rationale, design, and preliminary data from 3 ongoing clinical trials of mobile interventions developed for bipolar disorder or schizophrenia. Project 1 used a personal digital assistant to prompt engagement in personalized self-management behaviors based on real-time data. Project 2 employed experience sampling through text messages to facilitate case management. Project 3 was built on group functional skills training for schizophrenia by incorporating between-session mobile phone contacts with therapists. Preliminary findings were of minimal participant attrition, and no broken devices; yet, several operational and technical barriers needed to be addressed. Adherence was similar to that reported in nonpsychiatric populations, with high participant satisfaction. Therefore, mobile devices seem feasible and acceptable in augmenting psychosocial interventions for severe mental illness, with future research in establishing efficacy, cost effectiveness, and ethical and safety protocols.