The need to analyse policy networks (PNs) from an evolutionary perspective has been pinpointed by the three traditions of network research as one of the main gaps in the study of networking. This article examines successful networking practices in the Basque Country over an 18‐year period, taking in cluster associations, quality promotion and Local Agenda 21 promotion. Based on the Basque experience and on previous knowledge of PNs, we develop a new framework that explains their transverse evolution. We propose that asymmetric motivation, power dispersion and previous success are the main ‘disruptive drivers’ that explain why PNs come to life and evolve transversely by driving new PNs.