Engagement in Therapeutic Lifestyle Changes (TLCs), such as time in nature, physical activity, nutrition, sleep, social interaction, religion/spirituality, stress management, and helping others, provides many mental health benefits (Walsh, 2011). Young adults could particularly benefit from the use of TLCs, as they are at greater risk of experiencing mental health concerns (APA, 2013). I devised an intervention to enhance TLC engagement in college students, and examined the impact this intervention (against a control intervention), had on self-efficacy expectations, outcome expectations, mental health locus of control, intent to increase TLC use, and TLC use at one-week follow-up. Participants were 459 undergraduates. Participants completed baseline TLC use and self-efficacy expectations measures, then were randomly assigned to either a Control or my TLC intervention. Participants then responded to items assessing: post-intervention self-efficacy expectations, outcome expectations, mental health locus of control, intent to increase TLC use, and TLC preferences. Additionally, 211 of these participants completed a one-week follow-up survey inquiring about increased TLC use. Results demonstrated significant changes in pre- to post-intervention self-efficacy expectations for participants in the TLC condition; however, that condition did not bring a significant change in TLC use at follow-up. Outcome expectations partially mediated the direct relation between post-intervention self-efficacy expectations and intent to increase TLC use. Mental health locus of control did not moderate either intent to, or follow-up change in, TLC use post-intervention, as hypothesized. Regression analyses demonstrated that self-efficacy and outcome expectations accounted for 43% of the variance in intent to increase TLC use, and self-efficacy expectations accounted for 11% of the variance in post-intervention TLC use at one-week follow-up. I offer discussion on the implications of my findings and directions for future research. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]