In this paper, we present the results of a multi-year study of the social computing practices of 179 adolescents (Mage=12.4 years, SD=1.3; range: 10-14) living in a majority-minority lower-income urban neighborhood in the Southeast U.S. We investigate shifting social media practices using annual surveys and focus groups. We describe participants’ social media use and motivations and show how that use has shifted over time. We show how participants identify social pressures and influences as well as specific behaviors including computer-mediated risky behaviors and self-harm. We discuss the implications of our findings for the CHI research community, including methodological challenges and the need for further study of computer-mediated harmful behaviors in youth populations. By demonstrating how large-scale trends are enacted on the ground, we describe participants’ uses, motivations and behaviors as they deal with the increasing influence of technology in their social lives.