Challenges inherent with the transition to col- lege are often accompanied by weight gain among college freshmen. Weight gain and dura- tion of obesity increase metabolic syndrome and cardiovascular disease risk in young adulthood, which supports the need for weight loss inter- ventions tailored to college students. The pur- pose of this investigation was to conduct a mixed methods pilot trial to determine the effi- cacy and acceptability of a semester long Inter- net- and incentive-based weight loss interven- tion for overweight/obese college freshmen. Par- ticipants (n = 27, aged >18 yrs, BMI >25) were randomly assigned to a 12-week social cognitive theory (SCT)-based intervention (Fit Freshmen [FF]) or a health information control group. The FF intervention also included modest financial incentives for weight loss. Primary outcomes included body weight/composition, dietary and physical activity (PA) behaviors, and psychoso- cial measures (i.e. self-efficacy, self-regulation) associated with diet, PA, and weight loss. Stu- dents in the FF intervention participated in focus groups to provide qualitative feedback on pro- gram structure and design. FF participants demonstrated significant reductions (all group differences p < 0.10) in body weight (−1.2 kg), fat mass (−0.6 kg), dietary energy (−673 kcal/d), fat (−37 g/d) and added sugar intake (−41 g/d), and increases in diet and PA-related self-regulatory skills at week 12 compared to control partici- pants (+1.0 kg, +1.1 kg, −334 kcal/d, −15 g/d, −13 g/d, respectively). No changes in PA were noted, but FF participants demonstrated increases in self-efficacy to overcome barriers to PA relative to control participants. Themes for content im- provement from focus groups included reducing email contact and increasing in-person interac- tions. Program characteristics that were posi- tively evaluated included incentives for weight loss and access to an onsite weigh station kiosk. Overall, this efficacious SCT Internet- and incen- tive-based weight loss intervention was well received and can be adapted for larger-scale use in the college population.