This thesis investigates how various text-talks, i.e. text-focused classroom discussions, may scaffold students’ reading of specialised texts in upper secondary school. The study consists of qualitative case studies based on classroom observations of two teachers’ History instruction, focusing on parts defined as text-talks. An intervention study was conducted where one teacher worked with two text-talk approaches. The research questions regard how students move in relation to the text in the text-talks and how text content is incorporated, what scaffolding structures emerge, and whether and how the text-talks differ. A secondary aim is to generate theories concerning the potentials and limitations of text-talk as a reading scaffold. Analyses were done in terms of text movability to show reading positions, intertextual cohesion to show relations between source text and text-talk, and scaffolding which includes peer scaffolding, teacher scaffolding and the text-talks as a scaffold per se. A methodological contribution is the development of a model for content-based analyses of authentic text-talks. The results show that in text-talks that work as a scaffold, students take the expected positions toward the text, and the talks are clearly related to the source text, by means of lexical and conjunctive cohesion that is often varied and built-out. For more demanding texts, the students show dynamic text movability and move between exploring contents, subject field and context. Other characteristics are either peer scaffolding showing dialogicity and negotiation of meaning, or teacher scaffolding enabling students to progress and develop tools for text reception. The intervention approaches seem to scaffold reading to a greater extent than text-talks within ordinary instruction where the framing is weak. In conclusion, the results suggest that both student- and teacher-led text-talks may scaffold reading, but they need to be well planned and prepared with a structured framing.