AIM: This paper describes the development and psychometric evaluation of the Assistance to Participate Scale (APS). The APS measures the assistance that a school-aged child with a disability requires to participate in play and leisure activities from the primary carer's perspective. METHOD: Mixed methodology using an instrument design model was used to complete two studies. First, a qualitative research design was used to generate items and scoring criteria for the APS. Second, a quantitative study evaluated the instrument using data collected from 152 mothers with children aged 5-18 years. Statistical analysis assessed the underlying structure, internal consistency and construct validity of the APS. RESULTS: Exploratory factor analysis revealed two correlated components, reflecting home-based and community-based play activities. Both subscales and the total APS scale showed good internal consistency. The APS correlated as predicted with individual domains and overall scores for other validated measures (Pediatric Evaluation of Disability Inventory caregiver scales and Pediatric Quality of Life Inventory) with correlations ranging from rho = 0.42 to rho = 0.77. The APS was able to discriminate between groups of children based on type of schooling (regular or segregated), need for equipment/assistive devices, frequency of lifting and disability. CONCLUSIONS: The APS provides professionals with a brief psychometrically sound tool that measures the amount of caregiver assistance provided to a child with a disability to participate in play and recreation. The APS may be used as an outcome measure and to evaluate and predict the amount and type of additional assistance families need to facilitate their child's participation in an important aspect of the child's daily life and development: play and recreation.