This book is aimed to present the research work done by authors on assembly lines. The overall book is composed of 7 Chapters. The first Chapter introduces the research contributions and detailed structure of the book. Chapter 2 shows the review of literature on assembly lines. Chapter 3 is aimed to show the theory related to the multi-objective optimization. Chapter 4 shows the original research work of Authors to describe proposed mathematical models of the assembly line problems which are investigated. Chapter 5 shows the developed methodologies to solve the considered assembly line problems. Chapter 6 illustrates different experiments with their corresponding results which are performed for each assembly line problem. Chapter 7 illustrates the conclusion and future research directions. This book illustrates the types of assembly lines and their corresponding research problems related to them. The book is presents, Single model assembly line balancing problem, Simultaneous balancing and sequencing of mixed model assembly line problem and Simultaneous balancing and sequencing of mixed model assembly line problems.