Originally delivered as a series of lectures, this volume systematically traces the evolution of the "spin" concept from its role in quantum mechanics to its assimilation into the field of chemistry. Author Roy McWeeny presents an in-depth illustration of the deductive methods of quantum theory and their application to spins in chemistry, following the path from the earliest concepts to the sophisticated physical methods employed in the investigation of molecular structure and properties. Starting with the origin and development of the spin concept, the text advances to an examination of spin and valence; reviews a simple example of the origin of spin Hamiltonians; and explores spin density, spin populations, and spin correlation. Additional topics include nuclear hyperfine effects and electron spin-spin coupling, the g tensor, and chemical shifts and nuclear spin-spin coupling.