This paper describes informal, small-scale leisure and nightlife districts or entertainment zones (EZs) which have developed in or near the downtowns of mid-sized and large American cities in recent years. Occupying older vernacular buildings in marginal areas of downtown, the bars, cafes, restaurants, nightclubs and performance spaces of EZs have developed largely without the large-scale design, planning, government action or subsidy common in formal urban entertainment districts. EZs demonstrate the popularity, resilience and flexibility of small-scale, vernacular architecture and urbanism and its importance in generating a vibrant and diverse downtown. The paper documents the design and performative characteristics of EZs in American cities and locates these places within current urban design and development theory. The findings from a Milwaukee, Wisconsin, case study together with evidence from other entertainment zones indicate that EZs possess individuality and a vitality lacking in formal urban entertainment districts. The paper concludes with recommendations for designers, planners and policy makers to reform current urban entertainment development practices.