Background: Telemental health (TMH) via videoconferencing or phone can increase Veterans’ access to mental health (MH) care. TMH can eliminate barriers including travel distance and cost, as well as physical limitations, caregiving responsibilities, and MH symptoms that can make leaving home difficult. Prior to COVID- 19, rates of TMH in VA were low (~9%). There was a dramatic shift towards TMH during COVID-19 to prevent infection, with ~50% of care delivered by phone, ~25% by video, and ~25% in-person. Benefits and drawbacks of phone, video, and in-person care must be considered when choosing a MH care modality. If patients, providers, and/or leadership believe that phone care is equivalent in quality to video and/or in-person, they may be more likely to choose this modality as it often has the fewest barriers to use; however, based on limited evidence, phone care may be lower quality than video and in-person. We need more nuanced analyses regarding: 1) the relative quality of phone, video, and in-person care (e.g., for more complex patients, for psychotherapy sessions versus shorter medication management appointments), and 2) patient preferences. As a clinical psychologist and HSR&D investigator with TMH experience, I am well-positioned to conduct this research. This proposal will provide key methodological training and advance me toward my goal of becoming a leading health services researcher and implementation scientist with expertise in telehealth. Significance/Impact: MH, telehealth, access, and quality of care are all major HSR&D research priorities. The increased use of TMH during COVID-19 has led to a wealth of untapped data through which we can examine the relative quality of TMH care as well as patient preferences across modalities, in order to improve care modality decision-making processes. Results, which will incorporate data from millions of patients and thousands of providers, have the potential to impact delivery of high-quality MH care on a national scale. Innovation: To our knowledge, there has been no published research that: 1) compares the quality and patient preference of phone, video, and in-person MH care, and 2) uses this information to develop and implement evidenced-based strategies to increase video use when clinically effective and preferred by patients. Specific Aims: Aim 1: Examine quality outcomes of phone, video, and in-person MH care (e.g., differences in MH hospitalization rates). Hypothesis: Video care will be equivalent to in-person care and superior to phone care for more complex patients (e.g., history of MH hospitalization, 3+ MH diagnoses) and for psychotherapy appointments. Aim 2: Qualitative interviews with MH patients, providers, and leadership. Research question: What are facilitators/barriers to video use based on stakeholder attitudes, preferences, and decision-making processes, and how do these factors vary between sites with high levels of phone, video, and in-person care? Aim 3: Develop/pilot imp...