Most social scientists agree that case studies are useful for "theory building," but ethnographic methods papers often look to survey research for case selection strategies. This is due to a common but untenable distinction between theoretical and empirical generalization, which obscures how theoretically inclined ethnographers make implicit external validity claims. I analyze several exemplary ethnographies to show that (a) the distinction between theoretically and empirically oriented ethnography revolves around competing conventions for making claims that others accept as provisionally externally valid, (b) comparative-historical sociology provides a framework for evaluating how theoretically oriented ethnographies make such claims, and (c) each approach to making validity claims is optimized by different kinds of cases. Empirically oriented ethnographies make inductive claims via "pointy" cases wherein a phenomenon is pronounced or bifurcated. Theoretically oriented ethnographers are like post-Millian historical sociologist who triangulate past studies with resolutive or negative cases to make constitutive arguments.