Fingerprints are complex and individually unique patterns in the skin. Established prenatally, the molecular and cellular mechanisms that guide ridge formation and their intricate arrangements are unknown. Here we show that fingerprint ridges are epithelial structures that undergo a truncated hair follicle developmental program and fail to recruit a mesenchymal condensate. Their spatial pattern is established by a Turing reaction diffusion system, based on signaling between EDAR, WNT and antagonistic BMP pathways. These signals resolve epithelial growth into bands of focalised proliferation under a precociously differentiated suprabasal layer. Ridge formation occurs as a set of waves spreading from variable initiation sites defined by the local signaling environments and structural intricacies of the digit; the propagation and meeting of these waves determining the type of pattern that forms. Relying on a dynamic patterning system triggered at different sites generates the characteristic types and unending variety of human fingerprint patterns.