The study of lattice varieties is a field that hasexperienced rapid growth in the last 30 years, but many ofthe interesting and deep results discovered in that periodhave so far only appeared in research papers. The aim ofthis monograph is to present the main results about modularand nonmodular varieties, equational bases and theamalgamation property in a uniform way. The first chaptercovers preliminaries that make the material accessible toanyone who has had an introductory course in universalalgebra. Each subsequent chapter begins with a shorthistorical introduction which sites the original referencesand then presents the results with complete proofs (innearly all cases). Numerous diagrams illustrate the beautyof lattice theory and aid in the visualization of manyproofs. An extensive index and bibliography also make themonograph a useful reference work.