Background: Parenting interventions like the Family CheckUp have demonstrated effects on child physical and behavioral health outcomes. However, access to these programs is limited, particularly for populations experiencing health disparities. Primary care settings have become recognized as a potential delivery system in which these programs may be implemented at scale. The purpose of this trial is to test the effectiveness of the Family CheckUp 4 Health (FCU4Health) program, an adaptation of the FCU for primary care, and assess program implementation in an integrated primary care setting. Methods: We will conduct a hybrid type 2 effectiveness-implementation trial in partnership with a primary care clinic in a low-income, majority Latino community. Families with 2-to 5-year-old children will be eligible to participate. Families will be randomized to receive the intervention (n = 130) or services as usual (n = 70) and will be assessed annually over three years. Outcomes are informed by the RE-AIM framework (i.e., reach, effectiveness, adoption, implementation, and maintenance). Effectiveness outcomes include child health behaviors (e.g., Dietary Screener Questionnaire), behavioral health (e.g., Strengths and Difficulties Questionnaire), and parenting (e.g., Proactive Parenting). Early stage implementation outcomes are also included (e.g., cost, acceptability, appropriateness, and feasibility). Effectiveness outcomes will be assessed via intent-to-treat (ITT) analyses. Implementation outcomes will be primarily descriptive with comparisons to prior trials of FCU4Health and the original FCU. Projected outcomes: This trial will provide evidence related to the potential of integrated primary care settings to deliver evidence-based preventive interventions with a dual focus on behavioral and physical health.