Background. Participation is an important, yet seldom studied, outcome after total knee replacement (TKR). Objective. The purpose of this study was to investigate the extent and predictors of participation and participation restriction among people after TKR. Materials and Methods. This study investigated the changes in pain, function, and participation scores (measured using a subscale of the Late-Life Function and Disability Instrument) from pre-TKR to ≤1 year post-TKR among a subsample of participants from the Multicenter Osteoarthritis Study (MOST) longitudinal cohort (MOST is funded by the National Institutes of Health). The proportions of individuals with participation restriction pre-TKR and ≤1 and ≤2 years post-TKR were calculated for all participants and for important demographic subgroups. The association between demographic and clinical factors and participation was estimated using linear regression. The association between demographic and clinical factors and participation restriction was estimated using logistic regression. Results. There were 292 individuals with outcome data ≤1 year post-TKR. Of these, 218 (75%) had data pre-TKR and ≤1 year post-TKR and 160 (55%) had data ≤2 years post-TKR. There were mean improvements in pain, function, and participation at ≤1 and 2 years. However, approximately 30% of the study sample had participation restriction pre-TKR and post-TKR, and the proportion decreased significantly only for those <65 years old. Non-whites had a higher proportion of participation restriction than any other subgroup (41% ≤1 year, 48% ≤2 years). Female sex and non-white race were associated with a worse participation score, and several demographic and modifiable factors were associated with participation restriction following TKR. Limitations. The time between pre-TKR and post-TKR assessment varied across study participants, and data were not available on their rehabilitation utilization. Conclusions. Although there was a mean increase in participation ≤1 year following TKR, participation restriction was common. The likelihood of low participation was increased among women, non-whites, and those with depressive symptoms, severe pain in either knee, or worse pre-TKR function. © 2013 American Physical Therapy Association.