William E. Cross Jr. is a prominent psychologist known for his work in the field of racial identity development. He is best recognized for his model of Black identity development, which outlines the stages individuals go through as they form their racial identity. This model has been influential in understanding the psychological experiences of African Americans. Cross has also contributed to the broader field of psychology through his research on multiculturalism and the importance of cultural context in psychological practice. His work emphasizes the need for awareness of racial and cultural factors in therapy and education, making significant strides in promoting diversity and inclusion within psychology.