Animportantsuccessfactor for the field of KDDlies in the developmentand integration of methodsfor supporting the construction and execution of KDDprocesses. Crucial aspects in this context are the (incremental)developmentof a precise problemdescription, a decompositionof this top level problemdescription into manageableand compatible subtasks which can be reused, and a selection and combination of adequate algorithms for solving these subtasks. In this paper wedescribe an approachfor supporting the systematic decomposition of a KDDprocess into subtasks and for selecting appropriate problem-solving methodsand algorithms for solving these subtasks. Ourapproachhas been partially integrated into the CLEMENTINEsystem and has been used to develop a real worldapplication in the area of prediction. Keywords : KDD-processes, User-support, Task Decompositions, KnowledgeAcquisition