A hitherto neglected phenomenon in international new venturing is portfolio entrepreneurship, which occurs when entrepreneurs found, own, manage and control more than one business at a time, with ownership of the new venture being distinct from that of the existing business ventures. This study introduces the phenomenon of portfolio entrepreneurship in international new venturing through a longitudinal study of a cluster of small and medium enterprises (SMEs) in Tasmania, Australia, where 6 of 11 firms in the cluster were international new ventures (INVs). The pattern of international portfolio entrepreneurship pursued by the Tasmanian entrepreneurs and coupling between firms is described. Key findings include the ability of portfolio entrepreneurs to leverage high-discretion slack resources, positive legitimacy spillovers, and learning effects and experimentation across loosely coupled INVs in the portfolio. The findings also identify dysfunctional elements of portfolio entrepreneurship, and cast doubt over the conventional use of 'the firm' as the focal unit of analysis in INV studies. A particular contribution of this study is to remind us of the richness and pluralism inherent in international new venturing.