PHOBOS is an experiment designed to study Au-Au collisions at RHIC. The apparatus consists of a 4{pi} multiplicity array and two spectrometer arms. The experiment is designed to measure the polar and azimuthal angles of most particles produced in the collisions and whether they are charged particles or photons. For approximately 1% of these particles, the two spectrometer arms will measure their properties in great detail. This includes many of the particles near mid-rapidity which are expected to show the most striking effects of any new physics which may occur. PHOBOS has proceeded from the Letter of Intent stage through Proposal and Conceptual Design Review to Construction Approval. It is anticipated that data taking will commence in 1999 when RHIC first provides beam.