The only form of knowledge about ethnicity that officially and permanently attaches to individuals in Kenya is the register of citizens kept by the National Registration Bureau, which issues ID cards. In this chapter, I briefly trace the history of the ID card in colonial labour control practices (not civil registration), but focus on the deeply ambiguous role of ethnicity in registration over recent years. I show how there is a disconnect between the lack of a place for ethnicity in law or regulation surrounding IDs, yet its continued presence in practice. I then examine several cases of minority ethnic community leaders engaged in what I call ‘code seeking’, where they successfully lobbied for recognition as ‘tribes of Kenya’ as a path to securing ID cards – de facto proof of citizenship for people otherwise stateless. However, I also show that other people, in this example, the Galje’el people, a sub-clan of Somalis, have not been and likely will not be successful with this strategy. This chapter draws our attention to the benefits of both classification and vagueness, while remaining vigilant about their risks.