In birds, various signalling pathways are implicated in the dermis-epidermis crosstalk that leads to feather morphogenesis. Among these is the BMP pathway, which is believed to inhibit feather formation, yet the evidence for it doing so is somewhat contradictory. On p. 2797, Michon and colleagues shed some light on this issue with their study and mathematical modelling of BMP signalling during feather formation in chicks. Their findings reveal that rather than acting just as inhibitors, different BMPs have distinct, sometimes antagonistic, roles in feather development. To distinguish these roles, the authors investigated the expression of BMP target genes and studied in vitro dermal fibroblast behaviour in response to different BMPs. From these and other findings, they generated a mathematical model - a reaction-diffusion model - that simulates feather patterning and accounts for the negative effects that excess BMP2 and BMP7 have on feather formation. From their results, the authors propose a new view of BMPs and dermis organisation that agrees with previous findings but not with their interpretation.