This article explores the relationship between anti-discrimination policy and existing social policies directed towards disabled people. It proposes a conception of ‘spheres’ of social policy, in which different spheres advance different dimensions of equality. Within each sphere, definitions of disability are based on relevant comparisons which determine who should be recognised as disabled for the purposes of the policy. Examples of definitions are given using material from a cross-national European project. Examples are also given where social policies provide for disabled people without defining a disability category. The implications of these findings for anti-discrimination policy are drawn out, and problems in defining disability for the purposes of ‘fourth generation’ equality rights are identified. It is suggested that there are limitations to the extent that equality policy can be founded on non-discrimination principles, and that a more substantive equality policy for disabled people needs to learn from debates and experiences within social policy.