Using the Person-In-Environment (PIE) theoretical framework, this diversity practice text teaches students how to think about their personal reactions and assumptions about diversity and what constitutes cultural competent assessment and intervention when working with a broad range of diverse populations. The diverse populations presented in the text are described within an ecological, strengths perspective. The authors' thesis is that, in order to work effectively with diverse populations, it is necessary to take into consideration the complex dynamics of social functioning and social oppression. The Person-In-Environment theoretical framework provides a basis for analysis of the social, economic, and political reality of these diverse populations. The text presents an affirmative practice approach and builds on the available diversity practice literature. This text can be used in diversity practice courses, courses on working with oppressed populations, and other practice courses (such as advanced practice) that focus on diversity issues.