This chapter is a critical examination of the growing literature dealing with the normative structure of scientific practice. More specifically, my intention is to analyze the presuppositions of Robert Merton's original formulation of the ethos of science and—the critiques of his position, thereby arriving at a provisional assessment of the current status of the theory of the normative structure of science. The critiques may be divided into four major issues; (1) the extent to which the norms of science are peculiar to science; (2) the actual conduct of scientists in various organizational and historical contexts and the extent to which their conduct is governed by the norms of science; (3) the "morality" of the moral imperatives of science; and (4) the relation between the scientific ethos and the development of scientific knowledge.