This volume is dedicated to the use of lattice theory in module theory. Its main purpose is to present all module-theoretic results that can be proved by lattice theory only, and to develop the theory necessary to do so. The results treated fall into categories such as the origins of lattice theory, module-theoretic results generalised in modular and likely compactly generated lattices, very special module-theoretic results generalised in lattices, and new concepts in lattices introduced by the author. Audience: This book will be of interest to graduate students and researchers whose work involves order, lattices, group theory and generalisations, general module theory, and rings and algebras.