This volume contains critical editions of the Theologia 'Summi boni' and Theologia 'Scholarium' of Peter Abaelard (1079-1142). They complement the editions of the Theologia christiana and of preliminary drafts of the Theologia 'Scholarium', prepared by the late E.M. Buytaert in CCCM XII. The Theologia 'Summi boni' is the earliest known version of Abaelard's treatise on the unity and trinity of God. It was condemned at the council of Soissons in 1121. The edition in CCCM XIII is based on all three known manuscripts of the work. Extensive use has been made of the Theologia christiana, both to correct the text of 'Summi boni' where the manuscripts are deficient and to illustrate the type of changes which Abaelard subsequently made to his text. The Theologia 'Scholarium' by contrast, provides us with Abaelard's most mature reflections on faith in God's nature. The complex process of its composition through a series of drafts is described in an introduction, as is its relationship to collections of Abaelard's sententiae. The edition presented here is based on the six most important manuscripts of the work as well as on the earlier drafts, with special attention paid to the corrections in the Oxford, Balliol College MS 296. These emendations were made by a fourteenth-century scribe from an exemplar containing revisions not found in any other manuscript of the Theologia. lt is argued that these changes were made by Abaelard as part of a settlement with Bernard of Clairvaux, reached soon after the council of Sens, held in June 1140. These changes made by Abaelard to the Theologia have never been fully edited before. The passages to which William of St Thierry and Bernard of Clairvaux took exception and which Abaelard subsequently modified have been identified and presented below the main body of the text. The editions contain concordances of scriptural, patristic and classical sources cited by Abaelard in all three major versions of the Theologia.