This report explores how to upgrade bus services in US cities that cannot practically implement full bus rapid transit (BRT) corridors due to demographic, land-use, political, and financial constraints. Guidelines for developing BRT corridors reveal a tension between an emphasis on comprehensive planning on the one hand, and incremental, flexible development on the other. A review of the literature discusses this tension, various BRT elements, and the impact of these elements on per- formance and ridership. Case studies of incremental BRT projects in four U.S. cities highlight the importance of considering the sociodemographic and institutional contexts surrounding bus priority projects. Longitudinal and cross-sectional sketch models, using corridors as the unit of analysis, offer some insights into the relative impact of BRT features and external factors. While BRT can be a promising mode for a range of contexts, service frequency and reliability improvements are the foundation for successful projects. Building momentum for sustained improvements in bus net- works is a challenge, and successful incremental BRT projects offer examples of how emphasizing reliability and projecting a clear, unified image across a range of applications can help meet this challenge.