Traditional regular education organises learners more or less according to age. This system generates serious problems for learners who lag behind and those who are cognitively most advanced compared to age-mates. A first research question asks which learning, instructional, organisational and ICT characteristics may optimally promote diagnostically adequate, flexible playing and learning processes for each learner in school. The answer is based on a review of research resulting in a theoretical model to improve learning processes and outcomes in school. A second question is whether development of optimal education in preschool results in the hypothesised learning effects with cognitively gifted preschoolers. This research question is answered empirically by reporting about a two-year experimental intervention project conducted in 37 Dutch preschools with 1,247 preschoolers of about 4-6 years old. Implementation of optimal education per preschool is checked by the researchers. Results demonstrate that degree of development of optimal education per preschool is statistically significant in explaining cognitively gifted preschoolers’ development in cognitive achievement and their behaviour in social and motivation respects. The conclusion is that the design of optimal education is promising and needs further attention and prolongation in preschool and onwards, to promote preventative and adequate learning for all.