This paper, which is based on the Omega Rho lecture given at the 1990 ORSA/TIMS meeting in Philadelphia, states the author's necessary and sufficient conditions for effective OR/MS. Then it describes the changing character of this field, considers some opportunities for it, addresses some human resources concerns facing it, and offers a view of what it will do in the 21st century. After addressing some concerns about the higher education culture, it then provides some conclusions about the future of OR/MS.