Developmental selective learning processes of elementary school age children were investigated using two types of incidental learning methodologies. The purposes of this study were to: (1) compare the effects of the two types of incidental learning paradigms, and (2) determine the influence of different kinds of stimulus relationships on children's performance at two developmental levels. Eight pairs of colored pictures were presented in each experimental condition. Incidental instructions were varied with respect to the absence vs. presence of a concurrent intentional task. Within both instructional conditions, pairs of stimuli were either conceptual, perceptual, or unrelated. Results showed that selective learning patterns of both younger and older children were significantly modified by type of incidental instruction and type of stimuli presented. Developmental differences were obtained with respect to amount of retention. Instructions omitting a concurrent intentional task were more effective with older children; instructions including a concurrent intentional task were more effective for young children. (Author/GO)