Successful vaccine development for schistosomiasis has been hindered by a lack of consensus on the type of immune response that would provide maximum levels of protective immunity and incomplete knowledge of the key antiparasite effector mechanisms. Many vaccine studies conducted in mice support type-1-cytokine-mediated effector mechanisms, while acquired resistance in humans correlates with type-2-cytokine-mediated responses. However, recent data from cytokine-knockout mice suggest that choosing between these opposing pathways may be less important than previously hypothesized, as discussed here by Thomas Wynn and Karl Hoffmann.