The family check-up: Relations between motivational interviewing fidelity and intervention outcomes in early elementary school.

The Family Check-Up (FCU) is a family-centered intervention that uses motivational interviewing (MI) to enhance parents' motivation for goal-directed change in parenting practices. The present study examined relations between FCU therapists' MI fidelity and (a) the proportion of parent change talk, (b) parent-reported positive parenting practices (proactive parenting and limit setting), and (c) parent- and teacher-reported child social, emotional, and behavioral concerns. Participants were a subsample of parents (n = 136) and teachers (<i>n</i> = 36) of children from the FCU intervention condition of a randomized controlled trial implemented at kindergarten entry. MI fidelity was measured in FCU feedback sessions with parents using the Motivational Interviewing Treatment Integrity Code 4.2.1. Binomial regression analysis and multiple linear regression analysis were performed to examine relations between MI fidelity and intervention outcomes. Results suggest that FCU therapists implemented MI with fair to good levels of fidelity. Several Motivational Interviewing Treatment Integrity summary scores were related to intervention outcomes. As hypothesized, Technical Global was associated with a higher proportion of parent change talk, Percent Complex Reflections was associated with higher parent-reported limit setting in first grade, and Total MI Nonadherent was associated with higher teacher-reported social, emotional, and behavioral concerns in first grade. Unexpectedly, Total MI Adherent was associated with a lower proportion of parent change talk. Taken together, findings suggest areas of MI fidelity that may be helpful to emphasize to maximize FCU efficacy. Implications for school psychology, study limitations, and future directions are discussed. (PsycInfo Database Record (c) 2026 APA, all rights reserved).