Dietary practices following gastric bypass surgery must encompass new restrictions on eating, prevention of nutrient deficiencies, and weight maintenanc e. Using a mixedmethods approach, this project aimed to uncover gastric bypass patients‟ experiences with long-term dietary practices and weight loss. All participants in this project were recruited from support groups in Upstate New York and were a mini mum of one year post-surgery. In-depth, semi-structured, qualitative interviews were used to gain descriptions of patients‟ experiences with dietary and weight management. Transcripts were analyzed using the constant comparative method, a grounded theory a pproach, and a constructivist perspective. The first analysis revealed participants‟ weight loss outcome trajectories, which were characterized by periods of weight change accompanied by dietary transitions and changes in dietary management. Participants‟ abilities to make cognitive and behavioral changes in dietary management following surgery differentiated their weight outcomes into one of three long -term trajectories: Maintained, Regain/Lost, or Regained. The second analysis uncovered complex, multi-leveled networks of goals, strategies, and monitoring behaviors. The four emergent main goals (Weight Management, Health, Avoid Negative Reactions, and Integration) were supported by lower level goals. Lower level goals were accomplished through a multitude of strategies. Monitoring methods were used to assess strategy effectiveness and goal achievement. An emergent hypothesis from this analysis was that monitoring behaviors were related to successful weight loss outcomes after gastric bypass surgery. To explo re this relationship, an on-line survey was developed to assess dietary monitoring (keeping food records and portion control methods), weight monitoring (self-weighing with a scale), and their association with current BMI, percent excess BMI lost, and percent weight loss maintained. Higher scores for dietary monitoring behaviors, being unmarried, and lower pre-surgery BMI were associated with lower current BMI and greater excess BMI lost, when controlling for age, sex, and time since surgery. Dietary and weight monitoring were positively related to percent weight loss maintained, however, once other variables were controlled for in the statistical models, the relationship was not significant. This project emphasized the complex and dynamic processes of weigh t and dietary change after gastric bypass surgery.