This article argues that in order to strengthen their impact in the world, philanthropic investors need to rigorously define their goals, be realistic about how to achieve them, and commit to continual, systematic improvement. The authors argue that many foundations and committed wealthy individuals have struggled to impose the necessary discipline on their grant-making that is required to achieve lasting change. For example, the absence of market pressures and the insular environment in which they operate means funders fail to objectively assess their performance and avoid making ‘hard decisions’ about the programmes and people they fund, say the authors. Three fundamental questions are suggested to keep philanthropy on track to achieve worthwhile change, especially in recessionary times when available funds may need to stretch further: How do we define success? What will it take to make change happen? How can we improve our results over time? The paper contains case studies of foundations that have successfully imposed self-discipline in the pursuit of excellence and ‘game changing’ results.