To what extent do Swedish Samis identify their ethnicity as Sami, Swedish, or both? How do they meet various criteria for being allowed to register as voters to the Sami Parliament? What factors predict ethnicities? These questions are studied in randomised samples from the electoral roll for the Sami Parliament. Applying Berry’s model of acculturation, four types are constructed—separated, assimilated, integrated, and marginalised. The findings show that the integrated represent the great majority of Samis. The two groups who tend to choose one of the identities—Sami or Swedish—represent less than one third when combined and are about equal in size. Those marginalised with weak ethnic identities represent 2%. Although all meet the self-identification criterion of being Sami, few meet each of some ‘objective’ criteria, e.g. being involved in reindeer herding, having Sami as the home language or having parents or grandparents with Sami as the home language. The main predictors of a stronger Sami identity are cultural symbolic behaviours and heredity. The main negative predictor of a stronger Swedish identity among Samis is the use of cultural symbolic behaviours, and the main positive predictor is a positive estimate on the Swedish public opinion’s interest in Samis. The findings are discussed in relation to Sami debates on indigeneity.