This article describes the medium term effects of a full time preschool program for 4-year-old children. The study compares 273 grade 2 primary level students who participated in this program at age four to 300 non-participating students The results indicate that the full time program had a positive effect on language and reading, but not on writing. Furthermore, the authors note a lower performance in mathematics and a lower frequency of prosocial and academic behaviours in the full time student group.