Searching for an adequate method to investigate human development (especially the development of theoretical thinking) Vygotsky and his collaborators developed the causal genetic method. The basic idea of this method consists in the investigation of psychic functions and structures by their formation under controlled conditions (for instance via a formation experiment in classroom). But is this method also applicable in instructional settings using modern communications media? This paper is an attempt to find an answer to the question: By what means is the investigation of the formation of theoretical thinking realizable through the application of the causal-genetic method in instructional settings using hypermedia and distance learning? However, a closer examination of the question itself shows that there are three interrelated aspects, namely: the investigation and formation of theoretical thinking: distance learning using modern communications media: the causal-genetic method. It will be shown that in a formation experiment learning with a hyper-media-educational program, which is based on the theory of learning-activity, students reach a new level of cognitive development which is characterized by the growing ability of complex and dialectical thinking. (Contains 6 figures and 9 notes.)