In accumulating knowledge, direct modes of learning are complemented by productive processes, including self-generation based on integration of separate episodes. Effects of the number of potentially relevant episodes on integration were examined in 4- to 8-year-olds (N = 121; racially/ethnically heterogeneous sample, English speakers, from large metropolitan area). Information was presented along with unrelated or related episodes; the latter challenged children to identify the relevant subset of episodes for integration. In Experiment 1, 4- and 6-year-olds integrated in the unrelated context. Six-year-olds also succeeded in the related context in forced-choice testing. In Experiment 2, 8-year-olds succeeded in open-ended and forced-choice testing. Results illustrate a developmental progression in productive extension of knowledge due in part to age-related increases in identification of relevant information.