This study explores the contemporary practice of Ethical and Socially Responsible Investment and concludes that it is based on an ad hoc construct of empirically derived principles, driven mainly by the commercial self-interest of large financial institutions and fund managers. It explores the relationship between investment and morality, to posit a background theory of investment ethics. The study then proposes a move away from the narrow focus of ethical investment to a broader concern for investment ethics. The study introduces the discipline of investment ethics and examines the criteria that form the basis of morality in investment decisions. The resultant theory is intended to be of practical significance in the business and investment domains and to assist potential investors to evaluate investment opportunities in the context of a consistent set of substantive normative ethical principles.