The predominant method for treating obesity has been suggesting and providing information on a controlled diet and, to a lesser extent, increased exercise. That approach has largely failed beyond the short term for many decades as obesity rates continue to rise. Therefore, leveraging improvements in psychosocial correlates of weight-loss behaviors has sometimes been suggested instead. The aim of this study was evaluation of targeted improvements in self-regulation and self-efficacy within a theoretically derived weight-loss program. Women with obesity (N = 103) participated in a year-long community-based program emphasizing self-regulatory skills development to counter lifestyle barriers/challenges to first exercise, then controlled eating. Within a structured treatment protocol administered by community facility employees--and based on tenets of social cognitive theory, self-regulation theory, self-efficacy theory, and coaction theory--self-regulatory skills were initially developed to foster adherence to exercise. Those skills were then adapted to promote eating-behavior changes, emphasizing fruit and vegetable intake. Improvements in measures of exercise self-regulation, eating self-regulation, and self-efficacy for controlling eating, their corresponding behaviors, and weight and waist circumference were significant. Greater within-participant carry-over of changes in exercise self-regulation to eating self-regulation was significantly associated with more weight and waist circumference reductions over both 6 and 12 months. Change in eating-related self-efficacy significantly mediated those relationships. The mean weight reduction of approximately 6% indicated positive effects on obesity-related health risks. The community-based setting indicated potentials for large-scale dissemination of theory- and evidence-driven behavioral obesity treatments focused primarily on self-regulatory skills development.