Cardiac rehabilitation (CR) is an evidence-based secondary prevention program for patients with cardiovascular disease (CVD) that aims to stabilize patients clinically and to restore physical function and health after a CVD event. It is well-suited to the needs of the aging Veterans Health Administration's (VHA) aging population which is prone to CVD in a context of comorbidity, frailty, and associated functional decline. Unfortunately, few eligible Veterans participate. Logistic challenges are a key barrier as few VHA site-based CR programs are available. The Promising Practice home-based CR (HBCR) is a VHA initiative that was designed to improve CR participation using a novel home-based approach. While HBCR has been demonstrated to be effective for Veterans who attend, only few participate. Many Veterans eligible for HBCR remain encumbered by comorbidity and frailty, and often lack confidence and/or perceived capacity for home-based formats of care. The Transition to CR (T2CR) intervention is a 2-phase program that aims to improve the process of HBCR and to thereby better respond to Veterans' needs. T2CR Phase 1 is a \~2 day face-to-face program between the initial CVD hospitalization and home that includes comprehensive assessment of holistic risks (CVD and non-CVD), functional limitations, and psychosocial circumstances. Individualized pragmatic plans are formulated to ensure HBCR is feasible, safe, and practical despite aggregate complexity. Goal setting, adherence reinforcements, and education are integrated; exercise practice is emphasized; and consultations for comorbid issues and telemedicine video facilitation are arranged. T2CR Phase 2 is HBCR that is enriched by the orientation, practice, consultations, supports, and goal setting that were initiated in T2CR Phase 1, as well as innovative exercise training techniques for patients who are frail and/or functionally impaired. T2CR is aligned with the already existing Coordinated Transitional Care (C-TraC) Program. C-TraC nurse practitioners currently hone medication management, medical follow-up, and education as hospitalized Veterans transition to home, but do little to guide recovery of physical function. By facilitating referral to the T2CR intervention, C-TraC care will be enhanced. Using a hybrid efficacy-implementation (type 1) design, the Transition to Cardiac Rehabilitation to Address Barriers of Multimorbidity and Frailty study is a randomized controlled trial to study T2CR versus usual HBCR in the VA Pittsburgh and Boston Healthcare Systems. Quantitative endpoints include functional gains (assessed using the Patient Reported Outcomes Measurement Information System \[PROMIS\] Physical Function measure) over 365 days as well as a 5-Times Sit-To-Stand performance measure. The number of CR sessions attended, rehospitalizations, and Healthy Days at Home will be assessed. Patients' perceptions of feasibility and acceptability of T2CR will also be evaluated. Providers' perceptions of T2CR will be evaluated as well; the Consolidated Framework for Implementation Research (CFIR) framework will be used to structure their insights. Patient and provider feedback will be applied to refine implementation strategies with the goal to ultimately extend T2CR throughout the entire ORH Promising Practices network.