This article presents evidence on peer effects among U.S. agricultural workers. On average, we find that a 10% increase in peer productivity increases focal worker productivity by 2.8%. This effect is modified by the ability and gender of workers and peers. Exceptionally slow workers are least responsive to peers and have pronounced negative spillovers on the productivity of their coworkers—their presence decreases productivity by 2%. Male workers are more responsive to their peers than female workers—a 10% increase in peer productivity increases the productivity of men by 3% and women by 2.6%. Workers are also generally more responsive to peers of similar ability and gender. Workers increase their speed the most when in the presence of peers with abilities just above their own. Male workers are more responsive to male peers than female peers, and female workers are more responsive to female peers.