The study was designed to test the hierarchy of difficulty in the acquisition of principles of class and conditional logic for 120 children of normal intelligence, and to compare the relative rates of logic development for those children of normal intelligence with the rate of logic development found in a previous study involving 120 gifted children (5 to 10 years old). Results of the Shigaki-Wolf logic test revealed that the difficulty hierarchy of normal Ss' class and conditional principles was similar to that of gifted Ss. Logic principles fell into three clusters: the easiest were affirming the antecedent, conclusion, and denying the consequent; intermediary were negative conclusion, minor premise, and class chain; and most difficult were linear and nonlinear transitivity, major premise, and conditional chain. Gifted Ss were at least 2 years accelerated over normal Ss. (Author/CL)