The traditional Bain/Mason paradigm of industrial organization (IO) offered strategic management a systematic model for assessing competition within an industry, yet the model was seldom used in the business policy (BP) field. IO and BP differed in their frames of reference (public vs. private), units of analysis (industry vs. firm), views of the decision maker and stability of structure, and in other significant respects. Development of IO theory during the 1970s has narrowed the gap between the two fields, to the extent that IO should now be of central concern to policy scholars.