Youth with physical disabilities experience restrictions to participation in community-based activities, which can lead to poor health outcomes. Currently, activity-based treatment approaches that are client-centered and implemented in the youth's natural environment are considered recommended practice. It is unclear, however, whether targeting intervention at the activity and participation level (e.g. playing boccia) can result in improvement of body functions (e.g., joint mobility, balance) as well as in participation - two key outcomes of pediatric rehabilitation programs. Research suggests that the opportunity to practice therapist-prescribed exercise programs is positively associated with physical gains. However, the impact of participation in a chosen real-life activity that is meaningful to the youth on a range of body functions has not yet been established and effective methods for testing complex individual-based interventions and outcomes are lacking. With funding received from the Canadian Institutes of Health Research, the investigators have proven the effectiveness of the PREP intervention, i.e., Pathways and Resources for Engagement and Participation, in promoting youth participation in meaningful activities across two provinces. Using the PREP approach, the purpose of this pilot study is to 1) employ an interrupted time series (ITS) design in order to generate preliminary evidence on the effectiveness of participants engagement in a 6-week community-based activity program (e.g., team sledge hockey) on 3 body functions (i.e., motor, cognitive and affective) as well as on the performance of the selected activity. An 18-week interrupted time series design with multiple baselines across 8 participants with physical disabilities (e.g., cerebral palsy, spina bifida) will be employed. Each activity, individually selected by the participants, will be analyzed using the task analysis approach in order to identify the underlying body functions necessary for the chosen activity. These functions, i.e., motor (measured using the Spinal Alignment and Range of Motion Measure, the Functional Reach Test, the Trunk Impairment Scale and the Jamar dynamometer), cognitive and affective (using the Behavior Assessment System for Children), will then be measured multiple times throughout the entire study, resulting in overall 32 trajectories of change in body functions (8 participants X 3 body functions) and additional 8 trajectories representing change in activity performance (using the Canadian Occupational Performance Measure). Two experts will independently analyze each trajectory using visual inspection and an innovative analytical solution, i.e., a combination of segmented regression and mixed-effect modelling, will be performed to estimate the overall effectiveness of the intervention across participants. This interdisciplinary research team, including three researchers in the field of childhood disability (occupational therapy, physical therapy and pediatric medicine), has partnered with seven key stakeholders and will work collaboratively throughout the research process. This early study in the area will build knowledge about alternative clinical trials that can generate evidence applicable to practice. Findings can eventually inform decision-making by guiding clinicians, families and policy-makers in appraising the benefits of participation-based therapies on improving functional capacities and actual performance of meaningful life activities. Describing the multiple benefits potentially generated by one single intervention can facilitate the development of efficient youth-engaging therapies, and thereby contributing to the improvement of the provision of pediatric rehabilitation services.