This chapter discusses the relationship between private law and anti-discrimination law. Both conceptually and politically, the relationship between these two fields of law is as close as it is problematic. The principle of equal treatment is a fundamental and indispensable element of modern constitutional orders – and of law in general. It is clear that this principle is binding for public authorities: governments must treat all citizens equally, the courts must decide like cases alike. The scope of the principle for private actors, however, is much less clear. Private law is based on the principle of private autonomy, and the autonomous decisions of private actors follow private preferences, not the principle of equal treatment. Private actors’ decisions, then, might have discriminatory effects.