Many of the issues both in educational theory and educational policy concern the effects of different factors on different outcomes. To answer such questions requires research approaches which can determine causal effects of educational factors on outcomes. However, since the 1980s educational researchers have to a large extent shunned away from questions about causality. The lecture describes some of the historical developments in the views on research on causal effects in the field of education and in other areas of research. It is proposed that the main reason why many researchers turned away from causally oriented research in the late 1970s was disillusionment with the possibilities of educational research to arrive at generalizable knowledge about causal relations in the face of the complexity of educational phenomena. However, as a function of developments in theory, method and data availability there is now reason to be more optimistic about the possibilities to make progress in causally oriented research. The lecture describes and discusses these possibilities.