Background: This Veterans Affairs (VA) Health Services Research & Development Career Development Award resubmission is a five-year plan that will enable the candidate, a staff cardiologist and specialist in cardiac rehabilitation (CR) at the VA Tennessee Valley Healthcare System, to develop and implement interventions to increase CR enrollment in Veterans. CR is an outpatient program including prescriptive exercise and cardiac risk factor education that is an essential therapy for patients with cardiovascular disease. This proposal will develop a tailored intervention to increase Veteran enrollment in CR. Significance/Impact: CR is widely underutilized, with less than 20% of eligible patients enrolling in CR programs nationally. CR utilization is particularly low among Veterans, with only 10% of eligible Veterans enrolling in CR programs. Though CR referral rates have risen substantially over the past decade, CR enrollment has remained static. It is imperative to study barriers to CR enrollment among Veterans that have already been referred to CR and develop interventions tailored to these individual barriers. Innovation: The applicant will develop a tailored intervention for increasing CR enrollment using the Obesity- Related Behavioral Intervention Trials model, a conceptual model for intervention development, as well as the information-motivation-behavioral skills model, a theory of behavior change that allows individual tailoring. Linking these models will produce new knowledge regarding behavioral intervention methodology as well as an innovative clinical intervention that can be delivered by nurses and other clinical staff at VA facilities. The proposed intervention aligns with current VA initiatives by supporting CR enrollment wherever is most convenient for Veterans (including VA CR programs, non-VA CR programs, and home-based CR programs). Specific Aims: Aims 1 and 2 comprise a sequential explanatory mixed methods study to evaluate barriers to CR enrollment among Veterans. The purpose of Aim 1 is to quantify barriers to CR in 100 Veterans hospitalized with ischemic heart disease using the previously validated Beliefs About Cardiac Rehabilitation Scale (BACRS). The purpose of Aim 2 is to reveal additional barriers to outpatient CR enrollment through qualitative interviews in 30 Veterans from Aim 1 who did not enroll in CR. Aim 3 focuses on the iterative development of a tailored intervention to increase outpatient CR enrollment in 3 groups of 5 hospitalized Veterans, characterizing the intervention’s feasibility and acceptability. In Aim 4, the tailored intervention will undergo proof-of-concept testing in a non-randomized group of 25 Veterans hospitalized with ischemic heart disease. The applicant hypothesizes that these Veterans will have a clinically significant improvement in BACRS summary scores after the intervention, representing a decrease in perceived barriers to CR. Methodology: Aim 1 will quantitate the burden of CR barriers am...