Diversity, which contains race/color, gender, national origin, sexual orientation, age, pregnancy, disability, religion, genetic information and so forth has long been an important issue in today’s organizations. Mismanagement of diversity triggers discrimination at work, leading to many negative work outcomes. To deal with this issue, it is crucial to understand the nature of the discrimination concept. For this purpose, this chapter sets out the concept of discrimination from different theoretical perspectives to explore why people discriminate. Moreover, it takes a look at different types of discrimination at work by presenting practical evidence. This chapter ends with the possible consequences of discrimination at work as well as the combating strategies to eliminate it.