Objective:This study aimed to assess whether the long-term effectiveness of the Melbourne Infant, Feeding, Activity and Nutrition Trial (INFANT) at 2 and 3·5 years post-intervention varied according to maternal education and age.Design:Two and 3·5 years post-intervention follow-up of the INFANT cluster-randomised controlled trial. Outcomes at both follow-ups included children’s BMIz-scores, physical activity (ActiGraph), television viewing (parental report) and dietary intake (3 × 24-h dietary recalls). Dichotomous moderator variables included maternal education (universityv. no university) and age (< 32v. ≥ 32 years).Setting:Population based.Participants:Families completing the 15-month programme (n492) were invited to participate in the follow-ups when their child was 3·6 and 5 years old.Results:At the 2-year follow-up, the intervention effects on vegetable (positive) and sweet snack (negative) intake were greater in children with higher educated mothers, whereas water consumption (positive) was greater in children with lower educated mothers. At the 2-year follow-up, the intervention was more effective in increasing water consumption in children with younger mothers and decreasing sweet snack intake in children with older mothers (opposite result observed at the 3·5-year follow-up). At the 3·5-year follow-up, children with younger and older mothers increased and decreased their consumption of savoury snacks, respectively.Conclusions:Moderation by maternal education and age were observed for some outcomes; however, clear patterns were not evident at both follow-ups, with little consistency across outcomes. This indicates that INFANT was more-or-less equally effective in children irrespective of their mother’s education level or age, which is important in community-based interventions.