OBJECTIVE To evaluate the impact of a health plan-driven employee health and wellness program (known as MyHealth Rewards) on health outcomes (stroke and myocardial infarction) and cost of care. METHODS A cohort of Geisinger Health Plan members who were Geisinger Health System (GHS) employees throughout the study period (2007 to 2011) was compared with a comparison group consisting of Geisinger Health Plan members who were non-GHS employees. RESULTS The GHS employee cohort experienced a stroke or myocardial infarction later than the non-GHS comparison group (hazard ratios of 0.73 and 0.56; P < 0.01). There was also a 10% to 13% cost reduction (P < 0.05) during the second and third years of the program. The cumulative return on investment was approximately 1.6. CONCLUSIONS Health plan-driven employee health and wellness programs similarly designed as MyHealth Rewards can potentially have a desirable impact on employee health and cost.