The Test of Logical Thinking (TOLT) is a written test of cognitive development constructed to be logically equivalent to specific Piagetian tasks. It consists of 36 open-ended items administered in a one-to-one situation. Subjects were middle to upper class, predominantly white elementary school students. The 168 students were randomly drawn from ages 9-15 with 24 subjects per age year. After each response, the subject was questioned for the reasoning behind his answer. Answers were scored correct or incorrect according to response and reasoning on that item. Two out of three questions for each subscale must be answered correctly to meet the set criteria. Results showed that sequencing items while validating scale scores against appropriate Piagetian tasks was partially successful. (Author/DEP)