This text for advanced undergraduate and graduate students guides the reader through a smooth progression from the most elementary ideas of molecular orbital theory to an understanding of the electronic structure, geometry, and reactivity of large molecules. It starts with simple molecules and proceeds to relatively large organometallic complexes. The slant is theoretical, but in the last chapter the authors strengthen the link between theory and experiment. Focusing on basic concepts, the authors take a qualitative approach, which enables this text to fill a void in the undergraduate curriculum. The book is intended as a core or supplementary text in an advanced chemistry course.