In the history of ethics, we come across many moral theories that have been formulated and advocated by moral philosophers belonging to different ages. Each of these moral theories, indeed, made a significant contribution to enrich the field of moral philosophy and to guide people to lead a virtuous social life. Every ethical theory provides certain moral principles and standards to ascertain the moral worth of individual actions and institutional policies. In order to resolve moral controversies in practical life, we need certain moral principles and rules to apply to the issues under consideration. This chapter includes a critical survey of some popular moral theories of the West.