The optimal jurisdiction size has been debated since Plato and Aristotle. A large literature has studied economic and democratic scale effects, but we have almost no knowledge of the effects of jurisdiction size on the effectiveness of local services. This is due to two methodological problems. First, selection bias and reverse causality often render change in jurisdiction size an endogenous variable. Second, there is a lack of empirical indicators of effectiveness, and most studies therefore focus on spending measures. Extant research thus studies economies of scale, leaving effectiveness of scale unexamined. We address both problems in a quasi‐experimental study of public schools. Our findings from the school area indicate that jurisdiction size does not have systematic effects on effectiveness. Our analysis therefore supports recent studies of economic and democratic scale effects that indicate that the search for the optimal jurisdiction size is futile.