This chapter analyses some of the annotating practices, in order to highlight the diversity and also the shared customs of reading and writing in the period, both in religious and in secular texts. It showcases three letter manuscripts that share certain features but are different in other aspects. The first manuscript is a collection of the Moral Letters from Seneca to his pupil Lucilius, Paris, BnF, lat. 8658A. The second manuscript is a collection of letters of St Paul, edited and put together by Florus of Lyon, Bern, Burgerbibliothek, Cod. 344. The third one, Paris, BnF, lat. 2858, is the unique copy of the letters of Lupus of Ferrieres. From these examples, the chapter moves to observations on marginal practices in other manuscripts, to explore the personal annotation practices of ninth-century scholars.