Accumulating information and knowledge is a major task of development. A common assumption is that we build our storehouse of world knowledge, our semantic memory, through direct experience. Although direct experience is involved, to explain fully how we know all that we know, we also must consider processes that allow for integration of information learned in separate yet related episodes of direct learning, as well as inferential processes that operate over integrated representations and permit productive extension of knowledge. In this article, I describe the self-derivation through integration paradigm my colleagues and I developed to model these processes. Using this paradigm, we charted individual and developmental variability throughout childhood and in young adults. Several findings support the contention that the self-derivation through integration paradigm provides a valid model for how we build semantic knowledge, including the observations that performance on the task correlates with and predicts individuals' world knowledge and academic success.