Explanatory typologies have recently experienced a renaissance as a research strategy for constructing and assessing causal explanations. However, both the new methodological works on explanatory typologies and the way such typologies have been used in practice have been affected by two shortcomings. First, no elaborate procedures for assessing the general explanatory power of a typological theory on the cross-case level have been devised. Second, rigorous selection procedures for within-case analysis are lacking. Against this background, we introduce a systematic measure that helps researchers assess the explanatory power on the cross-case level, first, within the scope set by a particular typological theory and, second, by investigating the transferability of the theory beyond these scope conditions via an increase in the number of cases. Drawing on recent methodological works on nested analysis, we show how researchers can identify key cases for process tracing based on the cross-case explanatory fit of the typological theory. We illustrate the purchase of our procedures by revisiting seminal studies from the field of comparative historical analysis.