Existing methodologies for researching the lives of young people affected by migration have thus far oversimplified their physical mobility by focusing solely on their first international migration or that of their parents. However, previous research shows that migrant youth are mobile and that mobility plays an important role in their lives. This chapter presents mobility trajectory mapping as a methodological tool to record and study these varied mobility trajectories of migrant-background youth. Mapping trajectories allows researchers to employ a youth-centric and transnational lens by involving young people in the co-creation of knowledge about their experiences of moving between places, and by learning about the meanings they attribute to these experiences. This chapter presents our experiences in developing and implementing this method with 183 Ghanaian-background young people in Ghana, Belgium, Germany and The Netherlands as part of the multi-sited, interdisciplinary research project “Mobility Trajectories of Young Lives (MO-TRAYL).” By discussing methodological advantages of mobility trajectory mapping and presenting analytical insights into the nature of transnational youth mobility that it facilitates, we show that mobility trajectory mapping offers an alternative way to research migrant-background youth with potentially deep repercussions for how we understand their transnational lives.