This discussion of transitive inferences (if A greater than B & B greater than C, then A greater thean C) emphasizes an information processing analysis of logical thought. The two basic factors considered in such an analysis are (1) the task environment, including its structure, demands, decisions required, and information given; and (2) the individual as an information processor (his knowledge, limitations, etc.). In order to make transitive inferences a person must make several critical operations. He must know that the scale of comparison is transitive and must code task information. Research concerned with children's coding strategies is discussed to illustrate the importance of this operation. Young children (4-6years) can make the inferences if they are forced to code in certain ways (if their attention is directed to the comparative relations among key elements of the problem). A second basic operation is memory storage. Two possible models of storage are identified: (1) a coordinate model in which each ordered pair of items is stored, and (2) a spatial integration model in which information is integrated as it accumulates into one representation which is stored for subsequent inferential thought. Experimental work with adult subjects indicating that spatial representations are constructed in transitivity tasks is described. (DP)