To explain persistent gender gaps in market outcomes, a lab experimental literature explores whether women and men have innate differences in ability (or attitudes or preferences), and a separate field-based literature studies discrimination against women in market settings. We posit that even if women have innate ability that is comparable to that of men, their relative performance may suffer in the market if the task requires them to interact with others in society, and they are subject to discrimination in those interactions. We test these ideas using a large-scale field experiment in 142 Malawian villages where men or women were randomly assigned the task of learning about a new agricultural technology, and then communicating it to others to convince them to adopt. Even though female communicators learn and retain the new information better, and those taught by women experience higher farm yields, the women are not as successful at teaching or convincing others to adopt. Micro-data on individual interactions from 4000 farmers in these villages suggest that other farmers perceive female communicators to be less able, and pay less attention to the women’s messages.