Background: Overweight and obesity affect approximately one-third of Canadian children and these children are at an increased risk of developing life-long obesity-related health consequences. Treatment efforts in the pediatric setting focus on behavioural modification – including modification of dietary intake. Eating behaviours encompass a modifiable aspect of dietary intake and could be a useful approach for weight reduction in the context of pediatric weight management (PWM) programs. Objectives: 1) To describe changes in family, child and parent eating behaviours over a 12-month period after enrolment in a PWM program. 2) To examine if changes in family eating behaviours over the first 6 months in a PWM program can predict child BMI z-score at 12 months, even when controlling for other factors related to changes in BMI z-score. Methods: Children ages 2-17 with a BMI >85th percentile were included in this analysis. Data was collected at baseline, 6 month and 12-month timepoints as part of the CANadian Pediatric Weight management Registry. BMI z-score was derived from height (cm) and weight (kg). Eating behaviours (eating related to hunger (ERH) and eating style (ES)) were measured in children, parents and families using the Family Eating and Activity Habits Questionnaire. Child and parental scores were summed to generate a family score. Decrease in scores over time indicated improvements in eating behaviours. Results: 807 children were included in the analysis (48.3% male, 51.7% female, mean age 12.08, mean baseline BMI z-score 3.55). Family ERH scores decreased significantly from baseline to 6 months by 1.63% (-0.16 points, SD=0.09, p<0.05) but by 12 months scores were the same as at baseline. Child ERH scores decreased significantly by 2.06% at 6 months (-0.14 points, SD=0.02, p<0.05), but at 12 months scores were the same as at baseline. Parent ERH scores did not change significantly. Family ES scores decreased from baseline to 6 months by 1.88% (-1.99 points, SD=0.21, p<0.05) and stayed approximately the same at 12 months. Child ES scores were similar, decreasing 2.86% (-1.68 points, SD=0.03, p<0.05) from baseline to 12 months. Parents ES score decreased significantly by 6 months, but after 12 months, scores were the same as at baseline. Change in either family eating behaviours from baseline to 6 months did not predict child BMI z-score at 12 months when adjusting for age, sex and BMI z-score at baseline. In subsequent exploratory analysis, increases in child eating behaviour scores at 6 months was a significant predictor of increases in child BMI z-score at 12 months (p=0.02) when adjusting for age, sex and BMI z-score at baseline. Conclusion: In the context of PWM programs, eating style and eating for hunger improved over the first 6 months after enrolment. Improvements in child eating behaviour after 6 months could predict improvements in child BMI z-score after 12 months. / Thesis / Master of Science (MSc)