Recent trends show foundations are increasingly using more flexible and ‘trust based’ funding practices, such as practicing unrestricted grant making. Anecdotal evidence suggests that these practices will improve grantees’ organizational and project impact. However, there is limited academic literature in support of this assumption. We use a mixed-method approach combining case studies with longitudinal data analyses to study the causal effects of unrestricted grant making on grantees’ organizational and project impact, including their financial performance. In the Netherlands, the Dutch Charity Lotteries provide an excellent opportunity to examine the consequences of long-term unrestricted funding. The Charity Lotteries are one of the largest grant making foundations in the Netherlands, and they have been making large (>500,000 euro a year for at least five years at a time), unrestricted grants since 1989. The results of this project will provide insights in the significance of the Charity Lotteries that are important for researchers, grant-makers and professionals throughout the nonprofit sector.