The purpose of this study was to develop and validate two hierarchically related measures of concept generalizability. The two concepts were "Insect" and "Animal." The tests were organized in a novel format consisting of three degrees of stimulus complexity. The three degrees of complexity contained sets of pictures of each concept with each set of pictures displaying progressively fewer criterial attributes. The first set contained most immediate criterial attributes while the third set contained the most general. This organization assumed that children attaining the most general exemplars, demonstrating mastery of the concept, should be able to successfully identify exemplars in the two previous set of pictures. It was therefore hypothesized that the tests should conform to Guttman Scalogram requirements and that subjects unable to attain the first or second degree of complexity should also fail the third degree of complexity. The sample consisted of 144 children ranging in age from 6 to 11 years. Results indicated that both measures conform to the Guttman Scalogram requirements and thus constitute valid scales. It was suggested that these tests would enable a more quantitative investigation of concept generalizability. (Author/JN)