Research Impact Summary: Parents are important stakeholders in young children’s physical activity. Using the voices from parents and children from 117 families in the Growing Up in Ireland child cohort study, findings from this research captured the realities of a sample of Irish parents. Parents were heavily invested in the physical activity biographies of their children. Despite numerous challenges, key physical activity parenting behaviours included co-participation, facilitation, encouragement and involvement. Clear gender differences between mothers and fathers were found in their roles, beliefs and perceptions in relation to unstructured physical activity and highly organised sport. Social class, family contexts such as size and structure, as well as community resources and organisational factors influenced the extent to which parents could promote and harness physical activity behaviour in their children.