We seek to understand what is limiting women's access to finance, in particular for highly skilled start-up entrepreneurs. To investigate supply side constraints, we run a lab-in-the-field experiment in which loan officers in Uganda evaluate several business ideas based on real pitch decks from start-ups. We separate biases in idea evaluation from other constraints (such as gender specific differences in the ability to implement a project, or in external constraints that start-up entrepreneurs are facing). To do so, we randomly vary that loan officers observe an idea as coming from either a male or a female founder, and the idea as being implemented either by a male or female manager.