The problems are discussed of selecting and implementing a minicomputer system, with particular reference to the key stages in the various decision making processes involved. Following a brief description of a typical minicomputer, the range and purpose of the various system inputs and outputs is presented. This leads to discussion of: the function of the system; the type of equipment required to implement that function; the class of minicomputer suited to that requirement, assuming some form of minicomputer is appropriate; the type of system which should be purchased--i.e., in terms of hardware, software, systems support--with special reference to the individual responsibilities of user and supplier; criteria affecting the choice of supplier; and the particular items of software and hardware which should be bought. Close attention is paid to the sequence and interaction of the decision relevant to these topics, nonobservance of which often leads to considerable difficulty during the implementation and commissioning of the system. The article is intended for the relative newcomer to the minicomputer field who requires basic guidance in the optimum approach to minicomputer implementation in order to avoid some of the many obstacles with which he might otherwise be faced.