This longitudinal study focused on the extent to which mothers' beliefs about children's hypothetical social behaviors change over the transition period from early to middle childhood, and the extent to which they can be predicted from life circumstances and perceived social-support resources. Of an original sample of 122 mothers studied when their children were 4 years old, 45 were studied again 2 years later. As their children grew older, mothers' beliefs changed slightly. They believed more in the role of observational learning in acquiring social skills, became less inclined to attribute aggression and social withdrawal to age-related factors, became more negative about aggression in girls and less negative about it in boys, and increasingly favored low-power strategies for dealing with unskilled social behaviors. Mothers' later beliefs could be predicted from their earlier beliefs as well as from their current life circumstances and resources.