Several Latin American cities are replacing their semi-deregulated and dispersed public transport services by integrated public transport systems to overcome quality of service issues and multiple negative externalities. Cities can choose to implement their reform quickly – like Santiago, Chile – or gradually, as has been the case in the Colombian cities of Cali, since 2003, and Bogotá, since 2008. This paper reviews the experience of these two cities in an effort to help in understanding the impacts and issues behind the gradual implementation of integrated public transport systems, as they advance in cities of the developing world. Particular attention is given to the pace of implementation. The two cities present significant progress, despite the complexity of the process and protracted, yet-to- be completed, execution. The two case studies indicate that a very gradual approach may result in difficulties, resulting from discontinuities in political leadership and weak institutional capacity.