These Know, Care, Do case studies showcase how the male engagement approach was applied to programs and projects implemented in the Democratic Republic of the Congo, India, Nigeria, and South Sudan. Each case study follows the structure of the theory of change to illustrate how it can be applied to program design and implementation across diverse country contexts. The programmatic examples highlight ways to work with a variety of actors, institutions, and channels (such as religious leaders and the health system) to engage men and boys in family planning across the key roles as clients, partners, and agents of change and the core components of Know, Care, Do.