The Polycyclic Aromatic Hydrocarbon (PAH) Index, a special publication from the National Institute of Standards and Technology, provides the structures of a large number of PAHs. In addition to the structure, the Index lists other names for the compound, CAS number, molecular weight, length-to-breadth ratio, width, length, and thickness. Users can search the PAH Index via compound name and molecular weight, browse alphabetically, or scan cover to cover. An introduction to the Index is available in [.pdf] format.