An ageing population and a transition towards person-centred and integrated care create a growing need for health-promoting interventions that support healthy ageing among older adults. Social participation is an important determinant of health and well-being for older adults, yet social participation remains insufficiently addressed within health-promoting occupational therapy interventions, particularly in web-based formats.

The overall aim of this thesis was to explore and develop an understanding on how older adults’ social participation can be supported from individual, professional, and organizational perspectives. To achieve this, a stepwise research design was applied, informed by the Medical Research Council framework for developing and evaluating complex interventions. Four studies were conducted. Study I is a systematic review with a qualitative meta-synthesis of older adults’ experiences of using strategies to maintain and foster social participation. Study II is an exploratory case study examining older adults’ experiences of participating in the web-based occupational therapy group intervention Health Web, aiming to support older adults’ social participation. Study III is a convergent mixed-methods study evaluating feasibility and exploring preliminary intervention outcomes of Health Web. Study IV is a focus group study exploring organizational opportunities and challenges related to implementing health-promoting interventions for older adults, such as Health Web, within municipal health and social care.

Study I demonstrated that older adults strategically create and sustain routines for social participation through interconnected inward-looking and outward-looking strategies. Studies II and III provided insights into how strategies for social participation can be supported through the web-based occupational therapy intervention Health Web, with study II informing refinements of Health Web. Overall, findings from Studies II and III suggest that the intervention is feasible and acceptable and is perceived as valuable by occupational therapists and participating older adults. The findings further indicate that social participation can be supported by a combination of individual reflection, sharing of experiences within a group and the formulation of personalized goals. However, this potential was dependent on participants’ active engagement in both individual reflections and group dynamics, as well as their ability to participate in a web-based group format. This appeared to be facilitated when participants were fairly resourceful and had expectations aligned with the intervention’s content. Study IV highlighted that occupational therapists operate within organizational contexts that both enable and constrain health-promoting work. Organizational readiness for implementing health-promoting interventions was perceived as insufficient. The findings show that building organizational readiness requires coordinated, long-term efforts across the organization, rather than relying on specific professionals or isolated initiatives. For occupational therapy, these findings underscore the importance of engaging in ongoing dialogue, both within the profession and in interdisciplinary collaborations, on how more proactive and health-promoting approaches can be translated into everyday practice.

The findings of this thesis show how older adults’ social participation unfolds over time as a conscious and active process, in which choices of everyday activities play a central role. Supporting this process calls for a shift towards a more proactive, health-promoting approach in occupational therapy, where professionals facilitate older adults’ reflection and development of strategies for social participation. This, in turn, requires alignment across individual, professional, and organizational levels, supported by conditions that enable the implementation of health-promoting interventions. Taken together, these findings contribute knowledge on how occupational therapy expertise can be more effectively utilized in proactive health-promoting practice and provide a foundation for continued evaluation and future implementation of Health Web.