CAPRI is the collaborative network of all pediatric rheumatology investigators across Canada, with an outstanding track record of successful collaboration in a number of research projects. Since 2005 CAPRI investigators have worked on a project called ReACCH-Out, a team grant funded by the Canadian Institutes of Health Research (CIHR) to study the impact of arthritis on Canadian children. CAPRI developed a robust web-based longitudinal data base and enrolled 1,500 newly diagnosed children with JIA during a five year period. This study has resulted in one of the largest longitudinal JIA cohorts in the world and six published scientific manuscripts to date. Most importantly it has provided essential new answers about disease presentation and short to medium-term prognosis. The initial study was leveraged into two subsequent studies also funded by CIHR: Biologically Based Outcomes Predictors in JIA (BBOP) and Linking Exercise, Activity, and Pathophysiology in Canadian children with Arthritis (LEAP).