Objectives: Social participation has been consistently associated with lower risk of all-cause mortality, but studies have been ambivalent about how this association differs between men and women. The present study investigates if ethnicity accounts for gender differences in (a) the types of social activities older adults participate in and (b) the association between social participation and 4-year mortality. Methods: Data from 4,482 Singaporean older adults who participated in a nationally representative longitudinal survey were analyzed. Stepwise logistic regressions and Cox proportional hazard models with inverse probability of treatment weights were used. Results: Men were more likely to engage in social activities compared with women, but this gender difference varied by ethnicity for three activities. Whereas going out to eat was associated with a lower risk of mortality for men only, playing sports was found to be protective for women only, but these associations did not vary by ethnicity. Discussion: Findings suggest that although ethnicity may account for gender differences in the content of social activity participation, it does not explain gender differences in the association between social participation and mortality. More consideration should be given to whether each activity provides an appropriate milieu for the social interaction of each gender.