Risk reduction in cities of fast developing nations is both an opportunity and a big challenge. It is an opportunity because cities are considered efficient spatial forms of human habitation where smart interventions can be optimized. However, involvement and ownership of urban society is a big challenge. This paper illustrates these challenges and opportunities with an example of India's largest city - Mumbai. It discusses Mumbai's key drivers of risk, contributing factors to vulnerabilities and places it in the context of the 2005 flood - a disaster of a scale never experienced before. Citizen-government partnerships emanating from community-based small- scale initiatives for improving neighborhood's environment are analyzed. The paper concludes that there are enormous benefits in scaling up the participatory approaches, which result in reducing vulnerabilities and enhancing resilience of cities. Urban risk reduction will remain a daunting task if not built around these existing strengths of cities and their citizens.