Macromolecular Crystallography is a technique used to study biological molecules such as proteins, viruses and nucleic acids (RNA and DNA) to a resolution higher than ~5Å. This high resolution helps elucidate the detailed mechanism by which these macromolecules carry out their functions in living cells and organisms. Protein molecules can crystallize under regulated conditions; the crystals are made up of multiple copies of the molecule arranged in a regular 3-dimensional lattice. The x-rays deflected ("scattered") by the atoms in equivalent positions in the crystal lattice concentrate into sharp intense spots (crystal diffraction pattern). The macromolecular structure can be determined by analysis of the intensities and positions of the diffraction spots.

The Macromolecular Crystallography Group at the Stanford Synchrotron Radiation Lightsource operates and develops beamlines providing state of the art macromolecular crystallography facilities and support for visiting researchers. Of the beamlines currently operational BL12-1 and BL12-2, with an undulator source, are optimized for microfocus applications, but can also be used for conventional experiments (MAD, screening, etc.), while BL9-2 and BL14-1 are designed for MAD experiments. Researchers from universities, industry, and government laboratories around the world can gain access to the beamline facilities by submitting a research proposal.