The activation relationship is a new theorisation of father-child attachment that places the emphasis on exploration and openness to the world. This study, which was the first to employ the Preschool Risky Situation and which used a convenience sample of 51 father-child dyads, confirmed the hypothesis of an association between the activation relationship and internalising disorders (IDs) in children. The analyses demonstrated the existence of the anticipated link between underactivation and IDs: underactivated children had significantly more IDs than activated children. Children were underactivated when they received less encouragement to take risks and explore their environment and when they were overprotected through the exertion of more control than was necessary based on the potential danger. Also, the association between activation scores and IDs was significant after controlling for child temperament, parental behaviour, and the number of hours worked per week by fathers. The more positively activated children were in their relationship with their father, the fewer IDs they displayed. The exploration of links between the activation relationship and ID subscales revealed a unique connection to anxiety. This study could lead to the development of prevention programmes and interventions that include fathers. (Contains 2 tables.)