In 2020, individuals of all ages engaged in demonstrations condemning police brutality and supporting the Black Lives Matter (BLM) movement. Research that used parent reports and trends commented on in popular media suggested that adolescents under 18 had become increasingly involved in this movement. In the first large-scale quantitative survey of adolescents' exposure to BLM demonstrations, 4,970 youth (mean_age = 12.88 y) across the United States highlighted that they were highly engaged, particularly with media, and experienced positive emotions when exposed to the BLM movement. In addition to reporting strong engagement and positive emotions related to BLM demonstrations, Black adolescents in particular reported higher negative emotions when engaging with different types of media and more exposure to violence during in-person BLM demonstrations. Appreciating youth civic engagement, while also providing support for processing complex experiences and feelings, is important for the health and welfare of young people and society.