The relationships between brain functions and behaviour characteristics during various phases of the development of autistic children were looked into. In doing so, the concept of stability on the one hand as well as change on the other hand is the main topic and is illustrated with examples. The state of neuroscientific ideas and methodical possibilities on the theme is not only broached but also discussed in connection with the treatment (in the sense of an optimal coordination between brain and environment). It thus results that the connections between genetical disposition, brain development, environmental influences and behaviour in autistic children become more and more clear. Utilizing this, though, better treatment possibilities can only be expected on the basis of integrating bio-psychosocial research which emphasizes the development aspect.