This study tested certain implied predictions regarding conceptual learning at each of four sequential levels of development: concrete level, identity level, classificatory level, and formal level. For this purpose, scaled batteries to assess the level of conceptual development of children, kindergarten through high school, were constructed and a cross sectional/longitudinal study was begun in 1972-73. Four batteries are used in the study, one each for the following concepts: equilateral triangle, noun, tree, and cutting tool. Each battery has seven subtests, one for each of the four levels and one for each of three uses of concepts. The subtests can be scored to determine whether an individual has attained each level and each use. In 1972-73, to start the study, 50 boys and 50 girls of each grade group (kindergarten, third, sixth, and ninth) were tested. Based on preliminary results, five critical predictions were tested: (1) concepts are attained at four successively higher levels in an invariant sequence; (2) the level of concept attainment varies among children of the same age; (3) various concepts are attained by the same children at different rates; (4) concepts learned at the successively higher levels are used in understanding supraordinate-subordinate relationships; and (5) having the name of the concept and its attributes facilitates attainment of the concept and its uses. (CS)