This study investigates how exposure to a field of study influences students’ major choices. If students have incomplete information, exposure potentially helps them to learn about the scope of a field as well as how well the field matches their interest and abilities. We exploit a natural experiment where university students have to write a research paper in business, economics, or law during their first year before they choose a major. Due to oversubscription of business papers, the field of the paper is assigned quasi-randomly. We find that writing in economics raises the probability of majoring in economics by 2.7 percentage points. We show further that this effect varies across subfields: the effect is driven by assignment to topics less typical of the public's perception of the field of economics, suggesting students learn through exposure that the field is broader than they thought.