In the collection stage of the intelligence cycle, one has to determine relevant sources, access them and retrieve data from them. For each data class, many possible sources are available and determining the right ones is often difficult. Moreover, accessing sources and retrieving data may require a lot of effort. In this chapter, we present a tool for supporting the effective and efficient use of sources—the “source map.” In essence, a source map links data classes to sources and contains meta data about these links. These meta data indicate the adequacy of sources in terms of ease of access, ease of retrieval, and usefulness of the retrieved data. A source map can support the selection of appropriate sources (given a required data class), and it can support the assessment of the overall adequacy of available sources.