This book, first published in 1990, gives a general account of diagram manipulation techniques, as alternatives to algebraic methods of proof, in theoretical physics. Methods reviewed by the author include the popular techniques pioneered by Jucys and collaborators in the quantum theory of angular momentum and by Feynman in quantum field theory. The reader is encouraged to become bilingual in that many steps in the argument are presented as Problems, and are immediately followed by solutions and by comments on the method or proof and the significance of the results. This book will be of value to graduate students and research workers in theoretical solid state physics, atomic, molecular, nuclear and particle physics and theoretical chemistry.