Although cultural stress has been widely understood as a phenomena associated with immigrants, our study indicated that cultural stress is important in understanding self-concept of youth living in Puerto Rico. For boys, cultural stress, but not ethnic identity, is particularly important to their self-concept. Among girls experiencing high cultural stress, exploration and resolution of ethnic identity was associated with higher self-concept. Results suggested that the cultural stress associated with the colonial context of Puerto Rico is salient in ethnic identity and self-concept development, even though Puerto Rican youth are the ethnic majority in the island. (PsycINFO Database Record (c) 2018 APA, all rights reserved).