The extent to which teachers collect, interpret, and use information from multiple data sources is a key distinction between novice and expert data users. Understanding and exploring this dimension of teachers' instructional decision making requires a shift in contemporary perspectives toward the interconnectedness of data sources within teachers' practice of data use. In the present study, I develop and apply a conceptual framework for mapping the structure of connections between data sources within and across instructional practices. Findings indicate teachers typically use two to six data sources in the context of a given instructional practice, with considerable variation in the relationship between those data sources across instructional practices. Toward this end, the present study advances a typology for classifying teachers' preference for, substitution between, and complementary use of data sources. Findings have implications for preservice teacher preparation, in-service teacher professional learning, and research perspectives on data use in education.