Individuals with multiple sclerosis (MS) sometimes have barriers to social participation. The advent of the internet has created online support systems for social participation such as websites for individuals with MS. However, minimal research has been conducted about determinants of individuals' in-person and online social participation or how types of social participation contribute to emotional well-being. The present study aims are: (1) to assess the role of access to resources and other determinants as enabling in-person and online social participation, and (2) to analyze the association between social participation and emotional health of individuals with MS. The sample consisted of 508 individuals diagnosed with relapsing/remitting or secondary/progressive MS. Data from NARCOMS registry and data from original questionnaire on determinants of social participation and emotional health were merged. Logistic and linear regression analyses were performed. Individuals with access to the internet were more likely to participate online with friends (OR 5.47, p<.001) and the community (OR 47.7, p<.001). Individuals who regularly participate in in-person social participation with friends reported being happier (B=.38, p<.001), less depressed (B=-2.01, p<.001), and less anxious (B=-1.21, p<.001) than those who did not. However, there was no evidence of a relationship between emotional health and online social participation. Increasing access to in-person social participation with friends will likely have the most positive impact on emotional health. Future research should examine the aspects of online participation that are helpful or harmful.