Using five waves of panel data from 8,008 children in the ECLS-K, the current study compared children's academic performance growth curves from kindergarten through fifth grade among three types of nondisrupted and three types of disrupted families. The analyses found that children in nondisrupted two-biological-parent and nondisrupted stepparent households consistently made greater progress in their math and reading performances over time than their peers in nondisrupted single-parent, disrupted two-biological-parent, and disrupted alternative families with multiple transitions. These trajectory differences were either partially or completely accounted for by family resources in the kindergarten year (Time 1). Overall, our findings provided strong support for the resource-deprivation perspective and partial support for the instability-stress perspective.