Multiple factors can influence the rates of residential mobility flows between different regions of a country. Studies have often focused on demographic and economic factors, but social conditions may be relevant as well. We examined whether different indicators of social capital (i.e., social support, loneliness, social trust, community participation, cultural activities, and meeting other people) were associated with population migration rates across 299 municipalities of Finland. Data for the social characteristics were derived from the Regional Health and Wellbeing study (n = 100,750 respondents) aggregated to the level of municipalities using multilevel regression with post-stratification (median number of participants was 115 individuals per municipality, range from 5 to 10,616). Residential mobility rates were derived from census data. Municipalities with higher levels of social support, higher social trust, more cultural activities, and more frequent social contacts had higher net migration rates, that is, more people moving in than out of the municipality. Social support, cultural activities, and community participation were associated with higher in-migration. Social trust and frequency of meeting people were associated with lower out-migration. The findings provide empirical support for the hypothesis that regions with stronger social capital are more attractive destinations for within-country residential mobility.