The Wnt family of signaling proteins plays key roles in a variety of embryonic inductive events in vertebrates and invertebrates. This diversity appears to be mediated by differences in Frizzled (Fz) proteins, the cell-surface receptors for Wnt. Boutros et al. examined two Drosophila Fz proteins and found that, while they both activate the same signaling pathways, they do so with different efficiencies. The cytoplasmic domains of the receptors are largely accountable for this difference. Factored with differences in receptor-ligand affinities, this domain may be important in determining specific signaling outcomes.