A growing body of social scientific work has increasingly noticed that within and across nation-states, variations in major outcomes, including level of socio-economic development, patterns of voting, and macro outcomes of state capacity and democracy often display persistent correlations with variations deep in the past. Rather than seeking out proximate causes to explain contemporary outcomes, these findings suggest  the need to trace causal chains to the distant past to identify "deep" historical causes.  Among the greatest unsolved challenges of this mode of analysis, however, is a) settling on an “exogenous” starting-point to analysis, and b) identifying in parsimonious and data-intensive fashion the causal mechanisms that explain persistence. The collection of papers here represent some of the best empirical work being done among social scientists on how to conceptualize and implement a research agenda that explores the sources and mechanisms of long-run persistence.  Using an impressive mix of original local evidence, the papers leverage the insight that Europe’s colonizing or “Imperial” interventions potentially represent an exogenous “shock” on subsequent developments, shaping contemporary outcomes in Europe and elsewhere.  The papers explore the enduring impact on of Soviet imperial rule in western Ukraine after 1939 (Peisakhin); Prussian imperial rule along the Polish-German borderlands after 1895 (Ziblatt and Kashin); Soviet rule in the entire region after 1945 (Tucker and Pop-Eleches); and British imperial rule in south-western Punjab between 1880 and 1940 (Malik and Hussain).