People with multiple sclerosis (MS) can experience problems in interpreting others' emotions from faces or voices. However, to date little is known about whether difficulties in emotion perception in MS are related to broader aspects of social functioning. Also, there are few studies reporting the effect of MS on more ecologically valid assessments of emotion perception using multimodal videos. The current study looks at (1) the effect of MS on perceiving emotions from faces, voices and multimodal videos; (2) the possible role of slowed processing and executive dysfunction in emotion perception problems in MS and (3) the relationship between emotion perception and broader social functioning in MS. 53 people with MS and 31 healthy controls completed tasks of emotion perception and cognition, and assessed their levels of social support and social participation. Participants with MS performed worse than demographically matched controls on all measures of emotion perception. Emotion perception performance was related to cognitive measures in those with MS. Also, significant associations were found between emotion perception difficulties in MS and poorer social function. In particular, people with MS who had poorer emotion perception also reported lower levels of social support from their friends, and regression analysis showed that this prediction was maintained even when disease severity and cognitive function were taken into account. These results show that problems with emotion perception in MS extend to more realistic tasks and may predict key aspects of social functioning.