Cardiac rehabilitation (CR) services in the United States are underutilized and participation is particularly low for racial and ethnic minorities, low socioeconomic status patients, and rural residents. Reduced participation may not only indicate a failure in transitional cardiac care during the in hospital referral process but also could be due to barriers attributed to patients, providers, employers, or medical systems. In-depth analysis of this problem is impeded by difficulties with the identification of underserved groups in clinical settings. Disparities in CR participation certainly contribute to poor medical outcomes in these populations that stand to benefit greatly from lifestyle modifications. It is critical that CR providers survey their communities for underserved populations and coordinate creative efforts aimed at overcoming barriers to participation. Moreover, it is likely that referral to, and participation in, CR will soon be considered a quality indicator, providing further incentive for programs to optimize CR utilization among all eligible patients.