This study examined the effectiveness of a two-session preventive parenting intervention, the Parent Check-In. The intervention, grounded in Self-Determination Theory (SDT), is designed to facilitate adaptive parenting, specifically autonomy support, structure and involvement, and parenting efficacy, and to increase autonomous self-regulation and decrease behavior problems in children. Fifty-seven parents of 8–12-year-olds (M = 9.88, SD = 1.32) were randomly assigned to an intervention (N = 31) or waitlist (N = 26) group. The intervention included psychoeducation about SDT, parenting strategies, and practice applying these strategies to families’ situations. Parents and children completed questionnaires regarding parenting behaviors, children’s self-regulation, and child symptomatology. Relative to the waitlist participants, intervention participants showed positive changes on some parenting indices, though the effects sizes were modest. In particular, intervention participants increased in parental efficacy, decreased in parent and child reports of controlling parenting strategies, and increased in child reports of parent autonomy support. Children of parents in the intervention group reported decreased externalizing symptomatology. There was some evidence that the intervention was more effective for parents with lower levels of education and parents with children higher in internalizing symptomatology at pre-test. Although some effects were not significant, the results show the promise of the Parent Check-In as a brief, preventive intervention. Ways in which the intervention could be strengthened are discussed.