Background <p>Ensuring inclusive participation in daily physical activities is crucial and valid and reliable instruments are needed.</p> Aim <p>To evaluate the test-retest reliability and internal consistency of the self-reported web-based physical participation instrument, ActiveYou II.</p> Material and Methods <p>Reliability was examined in 41 children (mean age 10,5 years), and 41 adults (mean age 49 years) with disabilities using intraclass correlation coefficients (ICC), Kappa statistics, percentage of absolute agreement, and Cronbach’s alpha.</p> Results <p>The test-retest reliability was good for the participation frequency scores (ICC; 0.66 to 0.95) and moderate for the skill-competency and involvement scores (ICC; 0.43 to 0.89). The alpha values for internal consistency were acceptable for the frequency (α = 0.749), skill competency (α = 0.833), and involvement scores (α = 0.795).</p> Conclusions <p>ActiveYou II demonstrated good psychometric properties, indicating its potential to inform intervention planning and enhance service provision for individuals with disabilities. Lower reliability in skill competency and involvement scores suggests these factors are transient, varying with experiences, well-being, and mood. ActiveYou II maps and evaluates the interaction between individual and environmental factors, enhancing understanding of participation in physical activities.</p> Significant <p>Leveraging insights from ActiveYou II, stakeholders can enhance participation in physical activities and well-being for individuals with disabilities, thereby fostering a more inclusive society.</p>