Antibiotic resistance is a major threat to public health worldwide. As the healthcare sector's use of antibiotics is an important contributor to the development of resistance, it is crucial that physicians only prescribe antibiotics when needed and that they choose narrow-spectrum antibiotics, which act on fewer bacteria types, when possible. Inappropriate use of antibiotics is nonetheless widespread, not least for respiratory tract infections (RTI), a common reason for antibiotics prescriptions. We examine if pay-for-performance (P4P) presents a way to influence primary care physicians' choice of antibiotics. During 2006–2013, 8 Swedish healthcare authorities adopted P4P to make physicians select narrow-spectrum antibiotics more often in the treatment of children with RTI. Exploiting register data on all purchases of RTI antibiotics in a difference-in-differences analysis, we find that P4P significantly increased the share of narrow-spectrum antibiotics. There are no signs that physicians gamed the system by issuing more prescriptions overall.