Migration is a central determinant of population dynamics and structure. We examined whether three major temperament traits--sociability, emotionality, and activity--predicted migration propensity, selective urban-rural migration, and migration distance in a 9-year prospective study in Finland. The participants were Finnish women and men (N= 1,733) ages 15 to 30 years at baseline. The home municipality's position on the urban-rural continuum was assessed on the basis of the municipality's population density. We found that high sociability predicted migration to urban areas and longer migration distances. High activity increased general migration propensity (including migration to both urban and rural areas). High emotionality increased the likelihood of leaving the home municipality and decreased migration distances, but was not associated with selective urban-rural migration. These data suggest that temperament predicts the self-selection of environments on a demographic scale and may be relevant in understanding population dynamics.