Interorganization systems, as an element of electronic commerce, are rapidly becoming an essential resource for competitive success. At the same time, the capabilities of such systems are evolving themselves, coincident with augmented trading partner responsibilities and new organization strategies. This paper reports the results of a field study conducted to understand the way in which interorganization systems are advancing. Four stages of systems were identified. While each encompasses the capabilities of the preceding stage, their characteristics and the manner in which they are deployed are highly distinctive.