The question of what teachers should know and be able to do endures, given the central role teachers play in the development of young people into wise and contributing citizens for world societies. Research has demonstrated the relationship between teacher preparation and competence, and that quality teachers achieve better academic outcomes for learners. Moreover, the issue of quality teachers has become even more salient in the 21st century as forces of globalization blur boundaries, heightening both competition and cooperation among nations. These forces include: (a) massive global migration as a result of war and other political disruptions, such that countries around the world are receiving newcomers, many of whom are school-aged and bring with them new cultures and languages; (b) increased attention to human rights, with a focus on inclusion, equity, poverty reduction, and social uplift for all children, regardless of their circumstance or backgrounds, through universal education; and (c) international benchmarking assessments such as PISA (Programme for International Student Assessment) that are driving international conversations about quality education and educators. The demands on teachers have increased, and definitions of quality emphasize the ability to capably teach children who represent multiple diversities (race, language, national origin, gender identities) and multiple vulnerabilities (poverty, dis/ability, immigrant status). Preparing teachers for diverse students has long been relevant to the U.S. given its history as a country of immigrants, juxtaposed against a devastating legacy of enslavement, genocide, and imperialism. But the 1970s was when educators began to more seriously attend to educating diverse children who had been uniformly ignored because of racism, discrimination, and segregation. This was on the heels of civil rights legislature, activism on the part of people of color, people with disabilities, and indigenous people for better schools for their children, and large waves of immigration from Latin America and Asia, versus primarily European countries as in the past. As the proportion of non-white students increased in U.S. schools, preparing teachers for diversity became imperative, especially since the majority of teachers were white, and the achievement gap between mainstream children and diverse children remained stubbornly wide. Researchers also documented the inequities diverse learners faced in schools—poorly funded schools, less qualified teachers, limited access to academic curriculum, excessive disciplinary practices, and so on—as well as the teaching practices that made a positive difference in the educational experiences and achievements of diverse children. These included Culturally Relevant Pedagogy (CRP), meaningful learning that honors diverse students’ culture and communities, high academic standards supported by excellent teachers, and multiple access points into the curriculum. The solution to inequitable education requires that all teachers instruct and advocate for every student as if she or he mattered, that all students receive the same care and attention as the richest, most advantaged. This solution is deceptively simple because it requires teachers to examine and revise their own biases and misconceptions, and actively resist the persistent messages that depict diverse children as deficient, so as to see them as worthwhile, full of capacity, and on the brink of greatness.