Economists, engineers, and others to formulate and study methods to evaluate industrial research and development R&D projects. In this paper, my purposes are (1) to describe the results of recent studies to measure (ex post) the social benefits from industrial innovations, (2) to indicate the sorts of ex-ante evaluation techniques described in the literature and the extent to which they are used by American firms, (3) to provide measures of the biases and errors contained in ex-ante estimates of development cost, development time, and the profitability of new processes and products, and (4) to indicate the effects on probabilities of success of how quickly ex-ante economic evaluations are made.