Granulocyte–macrophage colony-stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF; also known as CSF1), granulocyte colony-stimulating factor (G-CSF) and interleukin-3 (IL-3) can each play a part in the host response to injury and infection, and there is burgeoning interest in targeting these CSFs in inflammatory and autoimmune disorders, as well as in cancer. For success in clinical medicine, therapeutic targeting will need to be delineated from current strategies. The individual CSFs have unique biological roles, suggesting that they could be used to target specific conditions. This Review compares the CSFs, with a focus on how they could be targeted, discusses the relevant clinical trial data and summarizes the potential clinical applications of targeting each CSF. Importantly, we discuss the novelty of CSF biology and attempt to clarify some of the surrounding misconceptions and issues that can affect therapeutic decisions.