This research investigates how three high school students in the USA developed new literacies practices through their participation in teenage Twitter. Data was collected from two sources, including archival data from participants' Twitter over a two-year span, and semi-structured interviews. Results found that teenagers developed a number of practices that facilitated orientation to cultural conventions of teenage Twitter, helped them mobilize followers for participatory events, and led to reflective awareness of how to tell stories on Twitter. This study suggests that teenagers used the affordances of Twitter in order to craft multimodal narratives that are co-constructed, participatory, nonlinear, and emergent. Thinking in hashtags, for participants, is a kind of action that serves to develop affinities of relation (to friends, to pop culture, and to new knowledge) through mediatized 'vital life stuff.'