Alain wrote three very large theological textbooks, one being his first work, "Summa Quoniam Homines". Another of his theological textbooks that strove to be more minute in its focus, is his "De Fide Catholica", dated somewhere between 1185 and 1200, Alan sets out to refute heretical views, specifically that of the Waldensians and Cathars. In his third theological textbook, "Regulae Caelestis Iuris", he presents a set of what seems to be theological rules; this was typical of the followers of Gilbert of Poitiers, of which Alan could be associated. Other than these theological textbooks, and the aforementioned works of the mixture of prose and poetry, Alan of Lille had numerous other works on numerous subjects, primarily including Speculative Theology, Theoretical Moral Theology, Practical Moral Theology, and various collections of poems.