Background. Social participation is considered to be an objective parameter for evaluating the success of transplantation. This study explores the association between posttransplant factors (kidney function, perceived side effects of immunosuppressive treatment, comorbidity, physical and mental health-related quality of life [HRQoL]) and social participation in patients 3 months to 6 years after kidney transplantation (baseline) and their impact on graft loss andmortality for up to 10 years (follow-up). Methods. At baseline, 331 patients provided their socioeconomic and medical data (comorbidity, kidney function) and completed the end-stage renal disease symptom checklist (perceived side effects), the Short Form Health Survey-36 and the Participation Scale. At follow-up, information on all-cause graft-loss and mortality was noted. Binary logistical regression exploring the effects of the independent variables on social participation and Cox regression analyses determining whether social participation predicted graft loss and mortality were performed. Results. Restrictions in social participation were associated with living alone, poorer kidney function, lower perceived side effects of corticosteroids, higher perceived cardiac and renal dysfunction, higher perceived posttransplantation distress, lower physical HRQoL, and fewer working hours. Restrictions in social participation increased the risk of all-cause graft loss 2.29-fold and the risk of all-cause mortality 11.94-fold during follow-up. Education, kidney function, and comorbidity also increased the risk for poor patient outcome. Conclusion. Kidney function, perceived side effects, comorbidities, and HRQoL affect social participation in patients after kidney transplantation. Additionally, social participation has a positive effect on long-term patient outcomes, decreasing the odds of graft loss and mortality over 10 years.