About 25 children in each of grades 3, 5, 7, 9, and 11 were tested in their ability to solve linear syllogisms, such as: John is taller than Mary. Mary is taller than Pete. Who is tallest--John, Mary, or Pete? Response latencies and error rates decreased across grade levels and sessions. Component latencies also generally decreased with increasing age. Four alternative information-processing models were fit to the group latency data at each grade level. These models were: (1) spatial, whereby the terms of a linear syllogism are represented in the form of a linear spatial array; (2) linguistic, whereby linear syllogisms are solved via inferences on functional relations represented by linguistic deep structures; (3) algorithmic, whereby people solve linear syllogisms by applying a series of simple, essentially mechanical steps; and (4) mixed, which combines selected features of the spatial and linguistic models, and adds new features of its own. The latency data supported the mixed model at each grade level, although in grade 9 the model was not the preferred one until the second session of testing. (Author/MH)