OBJECTIVE : This study sought to examine the efficacy of financial incentives to increase Medicaid patient participation in and completion of cardiac rehabilitation (CR). BACKGROUND : Participation in CR reduces morbidity, mortality, and hospitalizations while improving quality of life. Lower-socioeconomic status (SES) patients are much less likely to attend and complete CR, despite being at increased risk for recurrent cardiovascular events. METHODS : A total of 130 individuals enrolled in Medicaid with a CR-qualifying cardiac event were randomized 1:1 to receive financial incentives on an escalating schedule ($4 to $50) for completing CR sessions or to receive usual care. Primary outcomes were CR participation (number of sessions completed) and completion (≥30 sessions completed). Secondary outcomes included changes in sociocognitive measurements (depressive/anxious symptoms, executive function), body composition (waist circumference, body mass index), fitness (peak VO2) over 4 months, and combined number of hospitalizations and emergency department (ED) contacts over 1 year. RESULTS : Patients randomized to the incentive condition completed more sessions (22.4 vs. 14.7, respectively; p = 0.013) and were almost twice as likely to complete CR (55.4% vs. 29.2%, respectively; p = 0.002) as controls. Incentivized patients were also more likely to experience improvements in executive function (p < 0.001), although there were no significant effects on other secondary outcomes. Patients who completed ≥30 sessions had 47% fewer combined hospitalizations and ED visits (p = 0.014), as reflected by a nonsignificant trend by study condition with 39% fewer hospital contacts in the incentive condition group (p = 0.079). CONCLUSIONS : Financial incentives improve CR participation among lower-SES patients following a cardiac event. Increasing participation among lower-SES patients in CR is critical for positive longer-term health outcomes. (Increasing Cardiac Rehabilitation Participation Among Medicaid Enrollees; NCT02172820).