SUMMARYIt has been assumed that strategic decision making and implementation are both achieved through managers' sharing homogeneous cognitions of competition (e.g. Porac and Thomas, 1990). This paper tested the assumption of homogeneity of cognitions of competition, using a sample of 24 managers from the off‐shore pumps industry. A variety of cognitive mapping techniques were used and maps were compared using a self‐rating methodology. The results indicated that managers' mental models of competition are diverse, rather than homogeneous, but that this diversity increases as company boundaries are crossed and as functional boundaries are crossed. Therefore, it is concluded that future cognitive studies of competitive industry structures should assume diversity of cognitions rather than homogeneity. Specific propositions with regard to such research are drawn from the findi