A notable increase in the number of U.S. families choosing to homeschool their children in recent years has underscored the need to develop more systematic knowledge about this approach to education. Drawing on a theoretical model of parental involvement as well as research on families' social networks, this study longitudinally examines home- and public-school parents' motivations for home-based involvement in their fourth through eighth grade children's education at two time points. The study also examines whether involvement activities predicted student proximal achievement outcomes (academic self-efficacy, intrinsic motivation for learning, and self-regulatory strategy use) across the two groups. Results suggest that parental self-efficacy for involvement, specific invitations from the child, and parent social networks are positively related to home-based parental involvement across the groups, although home- and public-school parents recorded significantly different perceptions of personal self-efficacy, role activity beliefs, social networks, and child proximal achievement outcomes. Findings are discussed with reference to implications for future research and practice. (Contains 1 figure and 7 tables.)