This is a textbook on physical organic chemistry for advanced undergraduates and beginning graduate students, with the overarching goal to help students think beyond the simple models of introductory organic chemistry courses. Based on the author’s first-hand classroom experience, the text uses complementary conceptual models to give new perspectives on the structures and reactions of organic compounds. In the 3rd edition, the author thoroughly updates the topics covered including reordering the contents (so that computational chemistry can be used to explain conformational energies) to provide a more natural flow of topics, proceeding from substitution to elimination to addition. About 20% of the problems are either replaced or updated, with answers available in the companion solutions manual.