The papers in this document represent preliminary results of a study which is part of a 3-year project being conducted by the Educational Testing Service in cooperation with the New York City Board of Education, with support from the Carnegie Corporation of New York. This document is divided into seven sections: (1) Introduction, (2) Classification Skills, (3) Time Sequence Task, (4) Preschool Children's Understanding of the Coordinated Concepts of Distance, Movement, Number, and Time, (5) A Study of Number Conservation in Young Children, Under Two Materials Conditions, (6) Children's Understanding of Basic Language Structure, and (7) Discussion: Cognitive Growth in Preschool Children. A bibliography is included at the end of each section. (WD)