The International Benchmarking Network for Water and Sanitation Utilities of the World Bank's Water and Sanitation Program (IBNET) has been involved in water sector monitoring since 1997. It has set a global standard for performance assessment of utilities, with information from more than 4,400 utilities from 135 countries. This edition of the Blue Book summarizes the water sector status from 2006 to 2011. It adopts the 'IBNET Apgar' consolidated scoring system, which assesses a utility's health based on indicators that reflect the utility's operational, financial, and social performance, and a Water Utility Vulnerability Index (WUVI), a dynamic version of Apgar. Performance indicators of over 100 countries are featured in a statistical appendix. Since 2006, municipal water performance has improved despite accelerated urbanization and the impacts of the fuel, food, and financial crises. Overall coverage has increased, and piped water supply and wastewater services has become accessible to more people. Many operational and financial indicators have also shown improvements. An increasing number of utilities are operating in a corporate manner, and are actively handling water billing, collection, and water management through metering. Yet, since the financial crisis, coverage has not kept up with population growth due to a deceleration of investment in the sector. At the same time, labor and energy's share in total costs has increased, suggesting that the decline in investment has been accompanied by delays in maintenance. The results show that rapid economic growth can have a positive effect on utilities' performance, while improvements remain vulnerable to economic developments such as the fuel and financial crises.