The transition to primary school is an important time for both children and parents. The aim of this randomized controlled study was to assess the effectiveness of a Transition to Primary School Parent Program in strengthening parent knowledge and confidence to manage the transition process, increasing parent involvement in their children's learning, and improving child adjustment to starting school. Participants were 576 parents from 21 primary schools in Victoria, Australia. Results revealed that parents who received the intervention reported higher parental self-efficacy to help their children make the transition to school than parents in the control condition (i.e., routine transition practices provided by the school). These parents also reported greater parent involvement at school during the children's first term at school than parents in the control condition. There were no differences between the intervention and control groups on parent and teacher report of children's adjustment to school. This research is an important step towards developing empirically supported school transition programs focusing on parents. (Contains 1 figure and 5 tables.)