Do only technology companies have a corner on “network effects"—i.e. the magic that happens when users take on the work of growing networks to predominance because their transactional value is so clear? Think Facebook, Google, WhatsApp, Amazon, eBay, Uber, and the like. Or, is there a way to adapt this phenomenon to design equally omnipresent Changemaking Networks by harnessing changemaking network effects between systems that should work together for common good, but don’t—with technology as a possible enabler, but not a founding prerequisite? There is, says Sushmita Ghosh. In the first network effects playbook for social entrepreneurs, she presents the five core principles and accompanying strategies for pulling this off, distilled from extensive interviews with the founding entrepreneurs of 20 pioneering global Changemaking Networks. These have successfully orchestrated the coming together of several systems, their players, and concerned citizens to serve positive social change goals —such as "Zero Homelessness", "Health Care Without Harm" and "Holding Power to Account"—harnessing changemaking network effects. This playbook is a must-read for every social sector organization, company, funding agency, student, or concerned citizen who cares about a new way of organizing mass changemaking to outsmart and outpace the world’s biggest problems. Written for action-takers, it leaves every reader with a clear sense about how to get started on building Changemaking Networks. Today.