The present article examines the relationship between age and dominance in bilingual populations. Age in bilingualism is understood as the point in development at which second language (L2) acquisition begins and as the chronological age of users of two languages. Age of acquisition (AoA) is a factor in determining which of a bilingual's two languages is dominant and to what degree, and it, along with age of first language (L1) attrition, may be associated with shifts in dominance from the L1 to the L2. In turn, dominance and chronological age, independently and in interaction with lexical frequency, predict performance on naming tasks. The article also considers the relevance of critical-period accounts of the relationships of AoA and age of L1 attrition to L2 dominance, and of usage-based and cognitive-aging accounts of the roles of age and dominance in naming.