Biological sciences research at the ALS can be divided into two areas: general biology (microscopy/spectroscopy) and structural biology (crystallography/diffraction). These fields provide complementary approaches to the study of living organisms from the molecular to the cellular levels. Crystallography is used to determine the atomic-resolution, three-dimensional structures of proteins and nucleic acids—the building blocks of life—as well as complexes of these molecules, the interactions of which gives rise to biological processes. Microscopy allows us to find where these biomolecules are localized in the cell and visualize the cell’s overall organization. Spectroscopy also comes into play, yielding information on the chemical state of these molecules.