The paper suggests ways to coordinate basic social studies skills to achieve the goal of developing reasoning ability in elementary and secondary students. The first three sections present a rationale for teaching the reasoning process in the social studies curriculum. The author stresses that in order to be an effective thinker, one should be aware of the nature and structure of inductive and deductive conclusions. The next section categorizes skills according to three levels. The lowest level, facilitating skills, includes observation, classification, seriation, and spatial relationships. The second level, processes, comprises inferring, predicting, measuring, and formulating and testing hypotheses and models. The third level, operations, includes search, group participation, communication, quantitative interpretation, and social judgment. Together, the three levels are interrelated and move toward the refinement of reasoning abilities. The author then examines in detail the facilitating skill of classification. Classification is noted as the skill which forms the foundation upon which language use and development is built. Types of classification are disjunctive (either/or), inclusive (one set is a subset of another set), or some/all (overlapping sets). The final section discusses curriculum implications. A structure based on the development and interaction of the three skill levels is suggested. (KC)