Psychotherapy research results are viewed under the aspect of relevance and irrelevance for psychotherapeutic practice. The difficulties to develop effective research designs for children, and adolescents are described, and possible research perspectives are developed for this complex domain. Especially the amount of variables in combination with developmental stages of children, and adolescents creates extreme difficulties to develop research designs to give an answer to the question, which therapeutic approach is better than others in the near future. Some conclusions from research results are made for psychotherapeutic practice.