Evidence shows that transformational development initiatives in urban slums attain a much higher impact if they are designed to be reproducible. That’s why we work hard to measure our impact, document our progress, and systematize our efforts in order to make all of our projects reproducible. Scaling up successful initiatives not only increases their impact but also enables them to become more sustainable, because they tend to optimize their resources, develop innovative responses to the challenges they face and mobilize multiple partners to reproduce adapted project versions in other places, thereby multiplying the impact for many more people.