ABSTRACT: Most Canadian older adults do not meet physical activity recommendations. Researchers have investigated participation barriers and facilitators, with little consideration given to how specific factors influence activity participation for older adults. The purpose of this study was to identify unique factors that influence older adults' activity selection and to determine in which type of setting they are preferred. Using a two-phase methodology, identification of 25 factors affecting participation was followed by 45 older adults ranking the factors within four categories of activities: individual unstructured, group unstructured, individual structured, and group structured. Phase 1 analysis ranked each factor within each category. Further analysis found that there was a statistical difference between categories, indicating that older adults found different factors important, depending on the category of physical activity in question. This led to phase 2 analyses which identified three levels of factor groupings including the following factors: level A: fun, satisfaction, commitment, and energize; level B: safety, learning, awareness, internal motivation, and productive; and level C: meaningful contribution, intensity, and motivation. Additionally, some factors which were not identified in all categories were identified as unique to certain categories. These included creativity, hobbies, meaningful contribution, spiritual, competence, interaction casual, regularly scheduled, competition, self-efficacy physical, and team. This information can be used by individuals as well as program providers to nurture these factors within physical activity programs, which may lead to increased participation in this age cohort.