This study is a replication and extension of an earlier study, using a larger sample, a better measure of poverty status, and new longitudinal data. The study used path analysis to test hypothesized models of how the Parents as Teachers (PAT) program affects children's school readiness and subsequent third-grade achievement. Participants were 5,721 kindergarten children who were chosen to be representative of all children beginning public school in the state of Missouri in the fall of 1998-2000. These children were subsequently located in the state's third-grade test database 4-5 years later (82% of the original kindergarten sample). The causal models, which postulated both direct and indirect effects of PAT, were strongly supported by the data. EDITORS' STRATEGIC IMPLICATIONS: The findings add to the evidence that the PAT home visiting program holds promise as a primary prevention program. The authors demonstrate how parenting practices (including reading to children and enrolling them in preschool) promote both school readiness and subsequent academic achievement, but they also remind us of the pervasive effects of poverty.