Although we found that urban/rural residency and composition of slightly older adolescents showed moderating effects on behavior problems that paralleled those reported previously for alcohol use in later adolescence, we did not find significant moderation effects associated with migration for genetic or common environmental influences. The only significant moderating effect of migration was on the unique environmental component, which played a larger role in neighborhoods with higher levels of migration. This is consistent with what we have previously reported (Dick et al., 2007b; Rose et al., 2001a), in which most of the moderation effects we observed with unique environmental influences were such that unique environmental influences assumed greater importance in neighborhoods characterized by more opportunity and/or less social control. This is true here as well for both urban/rural residency and migration rates. However, we also observed significant moderation of the E component with percentage of older adolescents for both behavior problems and alcohol use, with unique environmental influences decreasing in importance as there were more older adolescents in the neighborhood, contrary to expected. It is not immediately obvious why this
