Despite enormous investments of time and money, can we manage to tackle the social and ecological challenges of our time? What if we could exponentially increase our impact? A new generation worldwide is seeking a meaningful purpose beyond greater profits. However, unlike companies, only a few social interventions have achieved significant large-scale impact. Inspired by modern innovation practices popularized by the bestseller "The Lean Startup," which have driven technological breakthroughs in all areas of our lives, Lean Impact focuses our attention on a new goal - radically greater social benefit. Social change is far more complicated than developing a new app. It requires more listening, more care, and more stakeholders. To make a sustainable difference, solutions must be embraced by the beneficiaries, address the root causes, and include a mechanism that can accelerate growth to achieve the necessary scaling.