This handbook is about the design of human–computer interaction (HCI) and of solutions for specific applications and domains. This chapter* is about how you can go beyond creating interfaces or improving user experience and make a difference in the world. That difference might be global, such as by doing work that supports the UN’s Millennium Goals, or it might be local in ways that are meaningful only to a particular community. The funding for the work may come from a government, a non-governmental organization (NGO), a research council, a charity, or a company; the budget may vary from the price of a ticket to millions of dollars. The people or group for which you hope to make a difference might be on the other side of town or on the other side of the world. Regardless, this chapter is about applying what we know about user-centered design (UCD) to worldwide economic and community Development.