This thesis contains a machine-readable edition of the text of the Speculum Vitae as attested in British Library MS. Additional 33995, with introduction and glossary. Claims for the possible common authorship of the Prick of Conscience and the Speculum Vitae are investigated firstly by Positional Stylometry, which provides no useful information. Many lines in the two poems are found to be similar, but a study of the similar lines casts doubt on their significance as an indication of common authorship. The study of similar lines leads to an attempt to define and isolate formulas. Differences between the poems are found in the use of formulas. Finally, the metre of the poems is examined and found to be more regular than previously supposed. Differences are shown in the metrical qualities of the poems. Although it cannot be shown conclusively that the Prick of Conscience and the Speculum Vitae are by two different authors, the arguments for common authorship are shown to be groundless.