Attribution studies distinguishes conventionally between internal and external evidence. Broadly, internal evidence is that from the work itself and external evidence that from the social world within which the work is created, promulgated and read; but there will always be overlap. Often one kind of evidence only acquires meaning by reference to the other. (Ephim Fogel proposed the use of ‘internal-external evidence’ for such cases, but that seems excessive for what is simply a distinction of convenience.) External evidence as treated here covers the following kinds:

1. Contemporary attributions contained in incipits, explicits, titles, and from documents purporting to impart information about the circumstances of composition – especially diaries, correspondence, publishers’ records, and records of legal proceedings;

2. Biographical evidence, which would include information about a putative author's allegiances, whereabouts, dates, personal ties, and political and religious affiliations;

3. The history of earlier attributions of the work and the circumstances under which they were made.

Internal evidence, to be considered in the course of the next three chapters, covers

1. Stylistic evidence;

2. Self-reference and self-presentation within the work;

3. Evidence from the themes, ideas, beliefs and conceptions of genre manifested in the work.

The second class of external evidence and the third of internal will inevitably overlap. The distinction in any given argument depends on whether the researcher is working inward from the context or outward from the detail of the text.