WW domains are small modules that mediate protein/protein interactions. In this issue of Structure, Aragón and colleagues show that a WW domain of YAP can mediate complexes with either the canonical PY motif in an inhibitory Smad or engage in phosphorylation-dependent complexes with one of the activated Smads. The propensity of YAP WW to recognize a pSP motif is a surprising find with a number of far-reaching ramifications.