In recent years, the degree of choice in education systems has increased in most countries. Still, the variation of choice policies across countries is substantial. The authors ask under what combinations of conditions (i.e. institutional features of education systems) choice policy succeeds in balancing educational efficiency and equity. Using the fuzzy-set qualitative comparative analysis, they investigate the impact of seven institutional conditions in 20 European countries. Those seven conditions are identified in school choice literature as relevant in explaining variations in educational efficiency and equity. The analysis shows that there are multiple causal paths to good policy outcome. The main contribution of this article is to show that "choice" is an INUS condition (i.e. an insufficient but necessary part of an unnecessary but sufficient combination of conditions) and that "no tracking" is a necessary condition for educational efficiency and equity. In addition, the authors show that "good management" and "competition" of schools contribute to good educational outcomes only in choice-tolerant countries.