Objective: A growing body of literature indicates that mobile health (mHealth) interventions that utilize smartphones for illness management are feasible, acceptable, and clinically promising. In this study, we examine how individuals with serious mental illness use a mHealth intervention–FOCUS–to self-manage their illnesses. Additionally, we explored participant perceptions of the intervention’s impact on their subjective illness experience. Method: We analyzed qualitative data from 30 individuals with serious mental illness who participated in 1 of 2 community-based, 3-month trials of FOCUS. In Study 1, weekly calls were conducted by a mHealth specialist to facilitate and enhance intervention use. In Study 2, researchers conducted qualitative interviews to gather detailed perspectives of intervention use. Data were sampled from the weekly call notes and qualitative interviews and analyzed using a thematic and collaborative approach. Results: Thematic analyses revealed 6 recurring themes. Three themes emerged in regard to participants’ ongoing daily use of FOCUS: “back-up” support, symptom management, and self-awareness. Another 3 themes emerged related to the intervention’s impact on participants’ recovery processes: acceptance of symptoms, motivation and supporting positive outlook. Conclusions and Implications for Practice: This qualitative study offers insight into how individuals with serious mental illness made use of a mHealth intervention designed to support illness self-management. Our findings suggest that individuals may benefit differently from mHealth interventions depending on where they are in the recovery process. As mHealth interventions become increasingly popular in clinical settings, it is important to understand consumers’ short-term and long-term benefits from these interventions. (PsycINFO Database Record (c) 2019 APA, all rights reserved)