Companies are turning to ideation contests to engage ideators outside company boundaries to solve their complex problems. Our research focuses on how articulating the problem, specifically the number and type of constraints described within the problem statement (brief), is related to the number of ideas submitted by participants in ideation contests. Specifically, we find that participant engagement, in terms of ideas submitted, varies with three different types of constraints—input, process and output. Contributions to the creativity literature as well as managerial implications are discussed.