This article investigates transitions at the level of societal functions (e.g. transport, communication, housing). Societal functions are fulfilled by socio-technical systems, which consist of a cluster of aligned elements, e.g. artefacts, knowledge, user practices and markets, regulation, cultural meaning, infrastructure, maintenance networks and supply networks. To understand how transitions from one socio-technical system to another come about, the article describes a conceptual multi-level perspective. The perspective is illustrated with a historical case study: the transition from horse-drawn carriages to automobiles in the USA (1860-1930). The case study shows that technological substitution approaches to this transition are too simpl...