Among individuals ages 15 to 19, suicide is now the second leading cause of death (Heron, 2016). Social media use is ubiquitous among this age group, with 95% of youth engaging in daily use (Burns et al., 2013). As vulnerable youth find each other through social media (Joiner, 2010), this trend can conceivably impact a large number of adolescents. School mental health professionals should be aware of this in order to mitigate the potential effects. This is the first of a two-part series on the context of social media in adolescent suicide prevention. Part 1 provides an overview of these issues. Part 2 continues with suggestions for harnessing the reach of social media to enhance suicide prevention, intervention, and postvention. [To view "Adolescent Suicide Prevention in the Context of Social Media--Part 2: Suggestions," see EJ1234954.]