In criticizing communitarian views of justice, Amartya Sen argues that identity is not merely a matter of discovery but an object of reasoned choice subject to constraints. Distinguishing three notions of identity – self-perception, perceived identity and social affiliation – I claim that the relevant constraints implied by this argument are minimal. Some of Sen's arguments about perceived identity and social context do not establish any further constraints. Sen also argues that a model of multiculturalism and some forms of education can restrict, or fail to promote, reasoned and informed identity choice. This argument is better understood in the light of Sen's work on capability and justice, notably his concern with ways in which underdogs can adapt and his emphasis on public reasoning. It highlights limitations on information and opportunities for reasoning. I suggest that these lead to genuine constraints on (reasoned and informed) identity choice. The paper focuses on Sen's work, though its claims are also relevant to George Akerlof and Rachel Kranton's analysis of identity.