This paper reviews the research and theories on ethnic identity development, and draws some implications from these ideas for improving curriculum design for, and instructional effectiveness with, ethnically different students, especially Black Americans. The paradigm of "the developmental stages of ethnic identity transformation" presented relies heavily on the research of Charles Thomas, William Cross, and James Banks, all of whom have developed different, though interrelated, typologies of this transformational process. The paradigm proposes how and why ethnic identity development should be included in the diagnostic profiles of students, along with mental, moral, emotional, psychological, and physiological development. The paper argues that this inclusion will ensure more diagnostic comprehensiveness and accuracy, and will help educators to better address the principle of "readiness" in curricular and instructional planning, thereby improving the overall quality of educational decision-making for, and service to, ethnic minority students. (Author/KH)