This paper presents an expert system that has been developed in the National Technical University of Athens and can be used for the selection of Production Planning and Control (PPC) software, that is going to be applied in a manufacturing firm. Both, a production systems taxonomy and a generic software package, are included in the knowledge base which has been created. The inferences made, are based on rules that relate PPC software with a set of production systems attributes. The results that are given by the expert system, include the whole architecture of the PPC software package which is applicable in a certain manufacturing setting.