This chapter introduces the reader to the repertoire of interference practices that regional communities use to promote democracy, security, and human rights. These include state monitoring (of elections and human rights practices) and crisis response in the form of mediation, sanctions, civilian missions, and military deployments. It also systematically measures variation across time (1960–2009) and space in the strength or status of the non-interference norm. It does so by tracing regional legal regimes relevant to non-interference and by comparing the interference practices of regional actors (using an original dataset). It argues that non-interference has long been weaker in Africa and Latin America than in Southeast Asia, and that this variation became more pronounced from the late-1980s onward, when regional interference converged on multilateral “liberal internationalist” practices. This chapter establishes the variation that the rest of the book seeks to explain.