A surface layer (``skin'') different from the bulk was found in single crystals of ${\mathrm{BiFeO}}_{3}$. Impedance analysis and grazing incidence x-ray diffraction reveal a phase transition at ${T}^{*}\ensuremath{\sim}275\ifmmode\pm\else\textpm\fi{}5\text{ }\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ that is confined within the surface of ${\mathrm{BiFeO}}_{3}$. X-ray photoelectron spectroscopy and refraction-corrected x-ray diffraction as a function of incidence angle and photon wavelength indicate a reduced electron density and an elongated out-of-plane lattice parameter within a few nanometers of the surface. The skin will affect samples with large surface to volume ratios, as well as devices that rely on interfacial coupling such as exchange bias.