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.