In business, it doesn’t take a huge company to launch a big idea. The Fortune Impact 20 highlights relatively small enterprises that have built their business models around world-changing ideas, using the profit motive to solve social and environmental problems. Our list, presented by TPG’s The Rise Fund, showcases venture- and private-equity-backed startups. These companies are typically earlier in their life cycles than the larger companies we feature on our annual Change the World list, but they’re deploying the creative tools of capitalism with an outsize positive impact—making people’s lives better even as they road-test and iterate on their innovations. In compiling the Impact 20, our staff focuses on companies that have already moved past the proof-of-concept phase and are now generating revenue and serving customers. (For more about how we choose the list, read our methodology. TPG is not involved in the selection process.) Some are already “unicorns” with multibillion-dollar valuations; others are smaller outfits with the potential to scale much bigger. But each is pursuing a vision that melds profit and purpose, building businesses that can do good while doing well.