Understanding adolescent climate change concern (CCC) may be a key strategy for building a citizenry that supports climate change action, as adolescents are likely less influenced by ideological polarization than adults. Prior research shows that climate education may build concern among adolescents, but other factors such as peer pressure may also be important. We investigated the relationships between CCC, acceptance of anthropogenic global warming (AGW), perceived level of acceptance among friends and family, and frequency of discussion of the issue among 426 middle school students in North Carolina, USA, and developed a novel instrument to measure each of these constructs. Acceptance of AGW had the strongest association with CCC. Frequency of discussion with friends and family was the second strongest predictor. Perceived level of acceptance among family and friends was the third strongest predictor. Model selection results suggest family had more influence than friends in this study. Girls perceived climate change as a higher risk than boys. In addition to building acceptance of AGW, leveraging discussions with peers and especially family may help build concern for climate change among future generations.