Understanding why employees go the extra mile at work is a key problem for many organizations. We conduct a field experiment at a medical organization to study motivations for employees to submit project proposals for organizational improvement. In total, we analyze 1237 employees, 118 proposals, and quality evaluations for more than 12,000 evaluator-proposal pairs. The analysis shows that solicitations offering a personal reward for top submissions boost participation rates without affecting submission quality. We show that this is due to workers partially internalizing the positive effects of their submissions on the other individuals in the workplace. We also find that offering employees project funding to implement their own proposals potentially backfires, undermining participation. And solicitations emphasizing mission-oriented goals, like improving patient care, are sensitive to the solicited person’s gender, with women responding more than men. These results shed light on the factors that drive employees’ engagement in organizational tasks, beyond regular duties, and provide insights on how to design incentives to foster contributions to public goods inside organizations.