Traditionally, entrepreneurs develop a detailed plan, find money to fund it, and then pursue it to its conclusion. But conditions can change drastically at any point you can end up locked into a process based on now-obsolete assumptions. The lean startup is all about agility and flexibility. Its mantra is build, measure, learn: create small experimental initiatives, get real-world feedback on them quickly, and use that data to identify what works and discard what doesn't. Gelobter explains exactly how nonprofits and advocacy organizations can adapt lean startup concepts to their unique circumstances. He offers dozens of real-world examples. The standard approach wastes time and money the lean startup promises to help social sector organizations vastly increase the good they do.