There are some difficulties in doing empirical research on Waldorf education: the underlying concepts and ideas are complex and hard to get into; and some of the expected results such as "individuality" and "freedom" are hard to measure in a reliable way. Some studies comparing Waldorf and mainstream students and graduates have nevertheless been done. Short summaries of such studies in Sweden, Germany, the USA and Australia are presented. One overriding result is that Waldorf students seem more interested to learn and more socially engaged than mainstream students, but somewhat less knowledgeable when it comes to facts and scientific explanations. This raises the question whether we want to foster knowledgeable but uninterested, or interested but less knowledgeable students. The empirical evidence also shows that only a few percent of former Waldorf students become engaged in anthroposophy.