We combine expertise in economics and psychology with scientific testing methods to shed light on what motivates people to give to charities. We partner with nonprofit organizations with which our academic research interests overlap with their practical research needs. Our objectives are two fold. First, we strive to improve the academic understanding of why, when, and how individuals give to charities, and second, we seek to help non-profit organizations achieve their missions by increasing the returns to their fundraising efforts. Much of the theory that describes the psychological drivers of behavior can be applied to the specific case of charitable giving. Through this research initiative we provide empirical evidence for the specific contexts in which particular psychological drivers compel people to give to charities and the contexts in which they do not. Nonprofit organizations in the U.S. ranging from community development organizations to environmentalist groups to trade associations send out millions of direct mail fundraising solicitations each year. The scale of the mailings and the disparate nature of the organizations involved make direct mail fundraising an ideal environment in which to evaluate these contexts. Through random assignment and precise manipulation of treatments we apply the strengths of the laboratory methodology to the imperfect real world. In so doing we not only improve the efficiency of nonprofit fundraising but also provide support for strengthening the standard economic model by incorporating omitted psychological drivers of choice. Through this initiative we conduct randomized trials to test marketing treatments designed to mimic the frames and cues that have been shown to influence choice in the lab. We conduct the trials through the large-scale direct mailings that many nonprofit organizations regularly send out. We work with organizations with medium to large-scale direct marketing campaigns and measure such outcomes as response rate, gift size, and other calls to action. To understand the contexts in which the treatments work and those in which they do not we conduct the tests across a wide range of sub-categories of organizations that comprise the nonprofit sector.