The goal was to study the impact of a teacher-directed and a child-directed pretend play on cognitive performance in a mixed-age environment. Twenty-six observations were performed on fifty-one kindergarten children with a mean age of 4.6 years (age span from three to six years) in two mixed-aged classrooms. Data were collected regarding children's affective and cognitive behavior according to generally accepted taxonomies; Bloom for the cognitive domain, and Krathwohl for the affective domain. A significant increase in cognitive behavior was found in child-directed play compared with teacher-directed play (113.1 ? 12.1 versus 45.7 ? 10.3, mean ? standard error of the mean; p is less than 0.0001). During child-directed play we found a significant positive correlation between children's cognitive and affective behavior (R =0.52, n=21, p is less than 0.014) and teacher's behavioral stimuli and cognitive behavior (R = 0.805, p is less than 0.001, n=21, n= 21), as opposed to teacher-directed play where teacher's stimuli correlated with children's affective behavior (R=0.905, p is less than 0.001, n=16). A balanced development of the cognitive and affective domains generates the main superiority of the child-directed play.