This article addresses the topic of transition and system change, and proposes endogenous regime transformation as alternative transition path to technological substitution. Using sociological and institutional insights, the dynamics of regime transformation are conceptualised. Two characteristics are pressure from outsider groups and adjustments in cognitions, norms and formal rules, enacted by regime insiders. The transformation perspective is illustrated with a historical case study, the hygienic transition from cesspools to integrated sewer systems in The Netherlands. The case study is used to make additions to the transformation perspective, particularly with regard to tactical and strategic games. © 2006 Elsevier B.V. All rights reserved.