The future of any industrial firm depends mainly on its development policy. This includes finding new products or fields of activity, developing them and then introducing them on the market. Research into new products and their subsequent marketing is still in many cases carried out on a trial-and-error basis. The purpose of this paper is to point the way to a more scientific approach to these problems. A firm can choose to expand its interests either by finding new uses for existing products or by developing entirely new products. This paper describes one way of approaching these problems -which in fact call for simultaneous treatment, with the first being related to short- and medium-term growth whereas the second has long-term implications. In the interests of clarity, however, they are dealt with separately. The method is illustrated by two concrete examples. Product-design and development proper are mainly the concern of the technical department of the firm. This stage, which precedes the introduction of the product into the market, will not be discussed in this paper.