A substantial proportion of medieval texts consists of other texts. Form therefore needs to be understood on at least two levels, by distinguishing between what can be termed ‘composite’ forms and ‘constituent’ forms. Some composite forms are fairly fixed (the Bible is a composite form); others are quite fluid. Genre, in this textual dynamic, is an elusive and contested notion. As illustrative case studies, this chapter considers two types of narrative: chronicle and hagiography. Hagiography is defined by subject (writing about saints), not by form as such. But hagiographic narratives tend to be produced and reproduced in large-scale composite forms organised according to closed annual calendrical cycles, while chronicles are compilations (often compilations of compilations) organised according to open-ended annalistic sequence. Between them these large composite forms contain most of the individual narratives that tend to be extrapolated in modern editions and discussed in modern critical writings, as literary works.