Lundquist K.-J. and Trippl M. Distance, proximity and types of cross-border innovation systems: a conceptual analysis, Regional Studies . Due to a lack of both theoretical and systematic empirical work, innovation-driven integration processes in cross-border areas are still poorly understood. Departing from the regional innovation system (RIS) approach, recent work on different forms of proximity, and the literature on cross-border areas, this paper seeks to identify in a conceptual way different stages in the development of cross-border innovation systems and to highlight the main characteristics and barriers characterizing each phase. The conceptual model proposed in this paper can serve as a useful framework, guiding more systematic and comparative empirical work on cross-border innovation systems in different regional and national contexts.