Semantic knowledge can be extended in a variety of ways, including self-generation of new facts through integration of separate yet related episodes. We sought to promote integration and self-generation by providing "hints" to help 6-year-olds (Experiment 1) and 4-year-olds (Experiment 2) see the relevance of separate episodes to one another. Varying the timing of presentation of the hints--whether provided between episodes or before test--afforded insights into the processes responsible for self-generation of new semantic knowledge through integration. In both experiments, hints provided immediately before testing facilitated performance relative to a control condition. In contrast, hints provided between episodes did not. The findings imply that integration of distinct experiences is not an automatic process set into motion based on shared elements. Even when integration is primed through a hint that a prior episode is relevant to a forthcoming experience, shared elements apparently are not sufficient to promote self-generation of new semantic knowledge. Instead, the process seems to occur upon demand, such as in response to a question. These findings can be used to guide interventions designed to promote enrichment of semantic memory and also further our understanding of the basic cognitive processes involved in extension of knowledge.