Behavioral screening and preventive intervention were implemented for 3- to 6-year-olds in pediatric primary care with subclinical behavior problems. One hundred eleven children were screened with the Eyberg Child Behavior Inventory. Thirty children who scored within one standard deviation of the normative mean whose mothers indicated wanting help for their child's behavior were randomized to one of two abbreviated versions of Parent-Child Interaction Therapy (PCIT) for use in pediatric primary care: (a) a 4-session group preventive intervention called Primary Care PCIT (PC-PCIT); or (b) written materials describing basic steps of PCIT and guidelines for practice, called PCIT Anticipatory Guidance (PCIT-AG). Decreases in child problem behaviors and ineffective parenting strategies, and increases in parental feelings of control were not significantly different between versions at post-intervention or 6-month follow-up. Changes during intervention were significantly larger for both groups than changes during pretreatment baseline, with moderate to large effect sizes. These brief versions of PCIT are both promising primary care preventive interventions that deserve further study.