The PEG Anomalous crystallization screens combine the design of the Ozma PEG series with 48 different anomalous salts that have a heavy atom ion component (cation or anion) with strong anomalous X-ray scattering behavior within the wavelength range generally useful for macromolecular crystallography (0.9 – 2.3 Angstrom). These heavy ions have been shown to bind non-covalently with high occupancy to the surfaces of protein molecules in crystals, providing an excellent means for single-crystal phasing via their anomalous scattering signal.