The Dino Study is a two-arm randomized controlled trial (RCT) designed to evaluate the effectiveness of the Incredible Years (IY) Small Group Dinosaur Child Program in young children (ages 4 to 8) with elevated or (sub)clinical levels of conduct problems. Conduct problems at this age are associated with long-term risks for poor academic, social, and mental health outcomes, yet current interventions rarely account for individual differences in children's emotional responsiveness and daily functioning. This study introduces the Dinosaur Program in the Netherlands and combines conventional pre- and post-intervention assessments with an intensive longitudinal diary design to examine both group-level effects and intra-individual mechanisms of change.
A total of 120 children and one parent per family will be recruited through partnerships with primary schools and mental health organizations. Families are eligible if the child is aged 4 to 8 years, has sufficient Dutch language skills, and shares daily contact with the participating caregiver. Children with an intellectual disability (IQ \< 70) or insufficient Dutch fluency will be excluded. After informed consent, families will be randomly allocated (1:1) to either the intervention or waitlist control condition. The intervention group will participate in 18 weekly 2-hour group sessions delivered by certified IY group leaders. The waitlist group receives care-as-usual and is offered the intervention after the posttest.
The Incredible Years Dinosaur Child Program is a structured, manualized group intervention based on cognitive-behavioral principles. It aims to enhance emotional regulation, prosocial behavior, and problem-solving abilities through playful, developmentally appropriate activities such as puppet play, role-play, group discussion, and storytelling. While parents do not receive formal training, they are indirectly exposed to program content through letters and reading assignments. The program has been widely implemented and evaluated internationally, but this study is the first to integrate it with daily diary methods to capture day-to-day variability in children's behavior and parent-child dynamics.
Primary outcomes focus on externalizing behavior, cognitive and social-emotional functioning, assessed via standardized parent, teacher, and child instruments. Secondary outcomes are derived from daily diaries and capture fluctuations in emotions, behavior, and dyadic emotional exchanges. Daily assessments will be collected using the m-Path app, completed jointly by parent and child every evening over a 20-week period (1 week baseline, 18 weeks intervention, 1 week follow-up). This approach enables fine-grained modeling of emotional variability and relational processes in the child's natural environment.
The study is informed by the Environmental Sensitivity Framework, which posits that children vary in their responsiveness to environmental input. Emotional sensitivity will be operationalized as moment-to-moment fluctuations in daily negative affect prior to the intervention. Multilevel and time-series analyses will be used to evaluate overall treatment effects as well as dynamic, intra-individual change patterns. Key hypotheses include: (1) children in the intervention group will show greater improvements in externalizing behavior and social functioning than those in the control group; (2) daily negative affect and behavior problems will decline more in the intervention group; and (3) intervention effects will be moderated by children's baseline emotional sensitivity.
Findings will contribute to the emerging field of precision prevention by identifying which children benefit most from structured group interventions and under what conditions. The integration of Intensive Longitudinal Data (ILD )with a randomized trial design allows for a mechanistic, personalized understanding of behavioral change in young children and their families.
