The National Center for Educational Statistics (NCES, 2010) continues to report substantial underachievement of diverse student populations in the nation's schools. After decades of focus on diversity and multicultural education, with integrating field and clinical practice, candidates continue to graduate without adequate knowledge, skills and dispositions to teach diverse students. The National Council of Accreditation of Teacher Education (NCATE) requires teacher education programs to engage in assessment practices that examine candidates' competence to teach diverse students and to inform the unit. In this article the authors discuss the need to triangulate the results of performance-based assessment and to systematically examine the growth of candidates' competence to teach every student. They propose a rigorous and systematic unit (i.e., teacher education program unit) assessment practice, using reliable and valid instruments to measure candidates' efficacy to teach diverse students, which will provide effective data for teacher education programs to become proactive to improve programs. (Contains 1 table.)