Background: Severe mental illnesses are consistently ranked as some of the most debilitating health conditions worldwide due to their early age of onset, chronicity, and impact on functioning. Fortunately, a number of antipsychotic medications have been found to be effective for managing the symptoms of severe mental illness (SMI) and for preventing relapse and rehospitalization. Despite their efficacy, treatment non-compliance for individuals on these medications is high due to a number of factors including poor insight into illness, negative attitudes about medication, and medication related side effects. Further complicating care and outcomes for this clinical population, providers must maintain close oversight of patients on antipsychotics due to the impact of these medications on metabolic and cardiac functioning which confer an increased risk of obesity, diabetes, heart problems, and other chronic illnesses. This oversight includes regular monitoring of weight, blood pressure, fasting blood glucose, and lipid levels. Additionally, clozapine, indicated for treatment-resistant schizophrenia, requires weekly-to-monthly monitoring of absolute neutrophil counts to prevent potentially fatal clozapine- induced agranulocytosis. Significance: The proposed project has significant and immediate relevance to Veterans and the VHA in that it seeks to better understand if and to what extent COVID-19 related care disruptions impacted care and outcomes for Veterans with SMI prescribed antipsychotic medications. Given pre- existing challenges in the treatment of this Veteran population, this is an important area of inquiry as well as one for which little is known. Added strengths of the proposed study include the use of a mixed methods approach that includes national level data from multiple sources. Aside from addressing a critical knowledge gap, the proposed study targets what is unarguably one of the most vulnerable patient populations within the VA and other healthcare systems—patients with SMI prescribed antipsychotic medications. Specific Aims: Aim 1: To assess the impact of COVID-19 related care disruptions on healthcare use and outcomes for Veterans on antipsychotic medications using robust statistical methods and national level data; Aim 2: To assess whether the impact of COVID-19 related care disruptions differ by race/ethnicity, gender, age, and rural/urban status using national level data; Aim 3: To conduct thematic interviews with provider and patient stakeholder groups at the national level to better understand COVID-19 related care disruptions. Provider stakeholders (e.g., psychiatrists, advanced nurse practitioners) will be interviewed to better understand COVID-19 related changes in practice behaviors, the perceived impact of these changes on care continuity and outcomes, and to solicit suggestions to mitigate the impact of interrupted care in the future; Veterans prescribed antipsychotic medication prescriptions in the pre COVID-19 window w...