Formation of the posterior of the vertebrate body involves cell movements like those that shape the anterior body during gastrulation, as well as cell movements that are posterior specific. Some of the genes needed for tail formation have previously been identified. Now, on p. 203, Marlow et al. propose that the transcription factor encoded by no tail(ntl; the zebrafish homologue of mouse brachyury) and components of the non-canonical Wnt pathway - encoded by pipetail(ppt) and knypek (kny) - function in parallel,partly redundant pathways to regulate the cell movements underlying posterior body formation in zebrafish. The double mutants kny;ntl and ppt;ntl both exhibit synergistic posterior trunk and tail shortening that the researchers show is not due to impaired posterior mesoderm specification and patterning, decreased proliferation, or apoptosis. Instead,convergence and extension cell movements, which also operate in gastrulation,and tailbud-specific subduction movements are all impaired in the double mutants.