Project GAIN (Golf: Accessible and Inclusive Networks) is a theory-based curriculum developed to promote an active life-style and inclusion of individuals with disabilities by enhancing their self-efficacy through golf. Over a 5-year period (2004–2008), 814 participants with and without disabilities from six cities across the USA formally enrolled in Project GAIN. Mentors were used to increase lesson participation, engagement between lessons, and inclusion in golf-related activities. For this study, data from 327 individuals with disabilities and 295 mentors with and without disabilities were used for analysis purposes. Data included measures of perceived self-efficacy in golf, future plans in golf, and a weekly log of golf-related activities. Paired-samples t-tests and repeated measures ANOVA were utilized to examine the effects of Project GAIN on participants’ intention to participate and actual participation in golf-related activities. Results indicated that both study groups (individuals with disabilities and mentors) significantly increased their self-efficacy in golf as well as their intention to play golf in future. Significant increases in golf-related activity were reported in weekly logs over the 5 weeks of data collection. Bonferroni post hoc tests were employed to examine mean differences between weekly observations. Significant mean differences between weeks 1 and 3, and 1 and 5 were found. The Project GAIN curriculum successfully contributed to improving participants’ belief that they could play golf. The study findings support the effectiveness of Project GAIN in increasing golf-related activities that may lead to increased inclusion and physical activity.