Crowdfunding websites like Kickstarter and Indiegogo offer project organizers the ability to market, fund, and build a community around their campaign. While offering support and flexibility for organizers, crowdfunding sites provide very little control to donors. In this paper, we investigate the idea of empowering donors by allowing them to specify conditions for their crowdfunding contributions. We introduce a crowdfunding system, Codo, that allows donors to specify conditional donations. Codo allow donors to contribute to a campaign but hold off on their contribution until certain specific conditions are met (e.g. specific members or groups contribute a certain amount). We begin with a micro study to assess several specific conditional donations based on their comprehensibility and usage likelihood. Based on this study, we formalize conditional donations into a general grammar that captures a broad set of useful conditions. We demonstrate the feasibility of resolving conditions in our grammar by elegantly transforming conditional donations into a system of linear inequalities that are efficiently resolved using off-the-shelf linear program solvers. Finally, we designed a user-friendly crowdfunding interface that supports conditional donations for an actual fund raising campaign and assess the potential of conditional donations through this campaign. We find preliminary evidence that roughly 1 in 3 donors make conditional donations and that conditional donors donate more compared to direct donors.