The quality of teaching and learning ecology is a critical ingredient into the cognitive development of children particularly in the early years of learning. This book gives the findings of a study on the impact of preschool human and material classroom environment in the cognitive development of preschool children. The study was undertaken in community-based preschools in East Africa (Kenya, Uganda and Zanzibar). Using an adapted version of Early Childhood Rating Scale(ECERS-R and ECERS-E),Teacher-Child Interaction Scale (TCIS)and a teacher pedagogical belief scale(TPBS) it was found that the kind of preschool programme,the quality of teacher-child interaction and the interactive material environment are significant predictors of children cognitive and academic achievement. Cognitive development was tested using an adapted British Ability Scale and a curriculum-based test developed by the researcher. It is recommended among other things that the Governments and communities in East Africa increase financial support, improve monitoring and evaluation of preschools in general and the teaching and learning environments in particular.