The study of marginalia has not been widely discussed in social sciences research and occupies a marginal space in terms of methodological legitimacy. We highlight the value of paying attention to the ways in which participants "speak back" to the researcher. This paper draws on marginalia found in surveys written or drawn by young people in classrooms across South Wales, demonstrating how various notes and marks made spontaneously by participants can tell us something important and worthwhile about how young people engage with research. We position marginalia as a manifestation of complex power dynamics in the research process that illuminate participants' negotiation of complex and multiple subjectivities in the literal margins and between the lines of the survey pages. Whilst the sensitive and rigorous analysis of marginalia is fraught with ethical and methodological challenges, we argue that paying closer attention to marginalia presents an opportunity for deeper engagement with participants when undertaking survey research.