This study addressed the effect of parent-child Mediated Learning Experience (MLE) interaction on cognitive development in early childhood. It measured the MLE interactions of 14 parents with their preschool children in the contexts of free-play and structured tasks. The children were assessed for their manifest cognitive performance and learning potential. A significant correlation between parents' MLE and children's optimal performance and cognitive modifiability was found. This study also examined specific MLE interactions in relation to optimal cognitive functioning. The parents' MLE during play interactions seemed to have more impact than their MLE during structured tasks. This raises the question of the role of play and playfulness when mediating young children's learning experiences. The findings support developmental theories which explore the relationship between play and cognitive development in early childhood. Specific MLE criteria were also found to be more related to cognitive modifiability. For a learning experience to effect cognitive development, there must be sharing of information and experience, together with sharing of affect, focus and attention, and communication of a feeling of competence. These findings support earlier studies on MLE as a factor of cognitive modifiability leading to increased benefit from both formal and informal learning opportunities.