This study analyzed YouTube beauty videos that focus on makeup for teens, based on the assumption that the main viewers of the videos are teens. Through looking at the interaction between beauty information providers and receivers, communication among information receivers, and the way people participate in comment thread, the study examined how teens engage in social media. Many teens who posted comments on YouTube beauty videos praised and envied the beauty of beauty gurus, and tried to connect with them. The comment thread shows that teens answered to each other’s questions on makeup tips, shared thoughts and experiences on issues around teen wearing makeup, which helped them build a sense of community, and broaden their views on the way of life. Also observed was power dynamics among youth, such as lecturing or verbal abuse against children and pre-teens by older teens.