Mexico has a long history of tensions between the government and student activists. This history dates back to student protests that ended with the State's violent repression of students in 1968. These tensions were reignited with the student occupation of Mexico's National Autonomous University from 1999 to 2000, which ended through intervention by the national federal police. In the 21st century, student expression and activism occurs in the physical world as well as on social media sites. For example, the hashtag #YoSoy132 was created by a student movement begun at the Jesuit "Universidad Iberoamericana" in opposition to the then candidate and now President of the country, Enrique Peña Nieto. In this paper, we conceptualize social media sites as virtual public spaces, and we employ cultural critical visual discourse analysis to examine the case of student "hashtivism," online activism through hashtags, in response to the forced disappearance of 43 students from the Raúl Isidro Burgos Rural Teachers College of Ayotzinapa in September 2014.