Transpersonal psychology represents a perspective which has gained importance in psychological research and clinical practice over the last years. This paper offers an overview on the history and the sources of transpersonal psychology. Additionally, important themes and topics of transpersonal psychology will be discussed such as a) the importance of spirituality in psychotherapy and counselling, b) spirituality as a resource for maintaining and regaining health, c) spiritual experiences as an avenue to consciousness, d) the delimination of extraordinary states of consciousness and "spiritual crises". In the next paragraph specific problems and critical points of transpersonal psychology are presented. Among them are the discussion of the question whether experience free of language is at all possible as well as the question how notions coming from eastern traditions can be translated into western psychology. Finally, some positive aspects of transpersonal psychology will be presented, and we submit that transpersonal psychology should be taken seriously in a scientific way.