The history of nitrogenase research dates all the way back to the 1800s. This chapter provides a brief account of the advances in this particular research area over the past few hundred years, which include such events as the initial discovery of biological nitrogen fixation, the preparation of active cell-free extracts, the purification of nitrogenase enzyme, the proposal of the Thorneley-Lowe model, and the report of x-ray crystallographic structures of the component proteins of nitrogenase.