As an integral step in a comprehensive, four year longitudinal analysis of concept development, a series of logical concept tasks based upon Piagetian theory, and suitable for administration to individuals five years of age or older, are described. The developmental focus was the logical groupements associated with the concrete operations period of middle-childhood. Sixty-four binary choice items were devised; one half of these assessed the operation of logical composition while the remainder assessed the inverse operation and reciprocal operation. In addition, complimentary concrete operations tasks, adapted from the procedures of previous normative investigations, were administered. These included dichotomous sorting, some-all understanding, class inclusion, cardinality, combinatorial reasoning, serial ordering, addition, and correspondence, transitive inference, and conservation of length, weight, and number. A sample of 180 children (equal numbers of kindergarten, and third and sixth grade male and female subjects) received the concept task series. Significant sex differences and order of presentation effects were generally absent. As anticipated, grade-level main effects were significant for the great majority of the tasks. Psychometric analyses were conducted, and it was concluded that the task series was a generally reliable assessment of logical reasoning. (Author/SD)