The assumption of equality undergirds the American law of employment discrimination. The assumption is that racial and sexual classes are equally qualified for jobs. Although it has sometimes been ignored, and can be rebutted in a specific case, the assumption of equality is fundamental to the law of nondiscrimination. Proof of discrimination in a class action, whether based on disparate treatment or disparate impact, requires the assumption. The assumption is so strong in this context that when the Supreme Court weakened it recently, Congress promptly reinforced it. The assumption of equality is also a crucial element of the law of affirmative action and reverse discrimination. The former is consistent with the assumption and is legal; the latter is inconsistent with the assumption and is illegal. By prohibiting race norming, which violates the assumption, Congress has reaffirmed its commitment to the assumption.