Investigated was the compatibility between the intellectual abilities of students and the level of intellectual operations required by secondary level physics textbooks. Student intellectual levels were determined for 949 tenth-, eleventh-, and twelfth-grade students by administration of Piagetian tasks. Major concepts presented in physics textbook chapters were classified as concrete or formal. Results indicated that 74% of physics students were at the formal level of operation and 40% of the potential physics students were at the formal level; all 130 major concepts analyzed from six physics textbooks required a formal level of operation. (SL)