Partnering both opens up and blurs the boundaries between organizations, and even expands them. Firms ought to shape their cooperation with other entities in accordance with their changing needs. A particular group of such entities is competitors. The question therefore arises whether partnering in relations with competitors (co-opetition) is suitable for all organization? This paper attempts to show what is involved in the adoption by Small and Medium-sized Enterprises (SMEs) of a partnering approach to extending their business base through co-opetition, how much it is needed, and how far it is possible in practice.