This document provides an introduction to a human-centered design toolkit. It is intended to help organizations enhance the lives of people living on less than $2 per day. The toolkit guides users through a process of hearing constituent needs, creating innovative solutions, and delivering solutions with financial sustainability in mind. It is meant to be adapted flexibly based on the specific design challenge and context. The toolkit contains sections on preparing for and conducting field research, translating insights into solutions, and planning implementation. It provides various methods, worksheets, and tips to facilitate each stage of the human-centered design process.