There is evidence that parents could influence the development of their children's effortful control in infancy through social interaction. Playful interactions in infancy often involve scaffolding - i.e. the parental provision of support and modelling for problem solving and learning during play. However, previous research has found little consistency over time in this type of parental scaffolding behaviour with infants. The present study had two aims. The first aim was to use a new, tiered coding system to assess the consistency of maternal scaffolding across toys (at the same time point) and over time. The second aim was to assess whether features of parental scaffolding related to concurrent or future measures of child effortful control. Thirty-six mother-child dyads engaged in joint play when children were 12, 18 and 24 months old. The following inhibitory/effortful control tests were administered: The 'Grasping Task', an object-retrieval task using a spoon laden with food at 12 months; Two delay of gratification tasks (Snack Delay and Gift Delay) at 24 months. The Bayley Scales of Infant Development Cognitive Scale was administered at 18 months. Maternal propensity to scaffold was the scaffolding behaviour that showed most consistency across toys and over time. Maternal contingency at 12 months predicted children's effortful control at 24 months. Sequential analysis indicated that maternal contingent interventions leading to children's successful actions could be the developmental mechanism underpinning the relationship between contingency and later effortful control. Maternal behaviour during play could lay the foundations for the strategic regulation of cognition and behaviour.