Diversity focuses on human characteristics that make people either different from or the same as each other. This article introduces the concepts of vertical and horizontal diversity. Vertical diversity evaluates difference as superior or inferior. Horizontal diversity treats difference as variation. Organizational paradigms of assimilation and separation are based on vertical diversity and treat diversity as a problem to be solved. Assimilation solves it by submergence of difference and separation by isolating difference. Often organizations in the United States take a benevolent assimilation approach to diversity. However, research shows that assimilation does not engage diversity in ways that promote learning, creativity, and organizational effectiveness. This article argues for a relational re-conceptualization of diversity as horizontal. The discussion integrates diversity paradigms with diversity perspectives, levels of self-representation, and uncertainty and certainty orientations to create an explanatory framework for the dynamics of diversity. (Contains 1 table and 1 figure.)