Background: Although schools are considered opportune settings for youth health interventions, a gap between school health research and practice exists. COMPASS, a longitudinal study of Ontario and Alberta secondary students and schools (2012-2021), used integrated knowledge translation to enhance schools' uptake of research findings. Schools received annual summaries of their students' health behaviors and suggestions for action, and were linked with COMPASS knowledge brokers to support them in making changes to improve student health. This research examines the factors that influenced schools' participation in knowledge brokering and associated outcomes. Methods: School- and student-level data from the first 3 years of the COMPASS study (2012-2013; 2013-2014; 2014-2015) were used to examine factors that influenced knowledge brokering participation, school-level changes, and school-aggregated student health behaviors. Results: Both school characteristics and study-related factors influenced schools' participation in knowledge brokering. Knowledge brokering participation was significantly associated with school-level changes related to healthy eating, physical activity, and tobacco programming, but the impact of those changes was not evident at the aggregate student level. Conclusions: Knowledge brokering provided a platform for collaboration between researchers and school practitioners, and led to school-level changes. These findings can inform future researcher-school practitioner partnerships to ultimately enhance student health.