The main purpose of this monograph was to add to the understanding of interrelationships of measures of concept learning within and across subject-matter fields and their relationships with basic cognitive abilities. This monograph reports on the entire project, drawing much information from prior published individual reports which are referenced. There were four major steps in the study: (1) identifying and analyzing basic concepts in language arts, mathematics, science, and social studies; (2) developing and studying tests to measure attainment of these concepts; (3) identifying and studying tests for cognitive abilities that seemed likely to be related differentially to concept attainment; and (4) studying the relationships between concept attainment and cognitive abilities. A major section of the report is devoted to each of these areas. In addition, another section summarizes the problems and implications and gives suggestions for further study. An appendix contains much of the data and analysis along with sample test questions and some critiques of the monograph. In all cases the grade levels used were fourth and fifth grades. (Author/LS)