Samples of 98 fourth graders and 111 sixth graders participated in a study of the relationships between operational thinking and reading comprehension of texts involving operational structures. Tests of operational thinking, reading comprehension, IQ, and vocabulary were administered in class groups. Results from correlational and factor analyses indicated that operativity and reading comprehension were significantly related and that this relationship was relatively independent of IQ and vocabulary. These findings were consistent with hypotheses derived from Piagetian theory. The relative development of operativity and reading comprehension was found to depend upon the operational stage. Operativity preceded reading comprehension for concrete operational tasks and succeeded it for the majority of formal operational tasks. Factor analyses indicated that tasks used in the study were independent measures of operativity and reading comprehension and that consolidation with each of these constructs occurs at different times in development. (Author/AA)