This chapter focuses on the distinctions between historical research and social scientific research, and how these are being challenged by scholars in pursuit of a genuinely ‘historical social science’. It begins with a discussion of historical approaches in Politics and International Relations, including historical events research, historical process research, and cross-sectional comparative research. It then examines three approaches for addressing temporality as the sequential active unfolding of social action and events: historical institutionalism, process tracing, and event structure analysis. It also explains how to locate essential historical information and evaluate various types of sources, and what special considerations need to be made in using documents, archival sources, and historical writing as data in historical research.