The notion of the ‘urban laboratory’ is increasingly striking a chord with actors involved in urban change. Is this term simply a metaphor for urban development or does it suggest urbanization by substantially different means? To answer this question, we review the work of science and technology studies (STS) scholars who have empirically investigated laboratories and practices of experimentation over the past three decades to understand the significance of these spaces of experimentation in urban contexts. Based on this overview of laboratory studies, we argue that urban laboratories and experimentation involve three key achievements — situatedness, change-orientation and contingency — that are useful for evaluating and critiquing those practices that claim to be urban laboratories. We conclude by considering some future directions of research on urban laboratories.