This article examines the representation of Shiʿism in three interrelated entries—“Shīʿa,” “Imāma,” and “Ithnā ʿAshariyya”—in the second edition of the Leiden Encyclopaedia of Islam. Wilferd Madelung authored the first two entries, while Seyyed Hossein Nasr wrote the third. The central question is whether their thematic proximity and cross-references produce a coherent account of Shiʿism or whether each entry follows a distinct epistemic logic. Using comparative textual analysis and source criticism, the study evaluates the entries according to seven criteria: definition, periodisation, evaluative language, the relationship between political and religious authority, citation practices, treatment of intra-Shiʿi diversity, and historical and legal accuracy. The findings identify three different explanatory regimes: “Shīʿa” offers a genealogical-political history of Shiʿi formation; “Imāma” organises Muslim theories of leadership within a historical-comparative framework; and “Ithnā ʿAshariyya” presents a largely Traditionalist, philosophical, and esoteric self-representation of Twelver Shiʿism. These approaches are partly complementary but diverge over the origins of esoteric Imamology, the relative weight of law and hadith, and the relationship between history and theology. The article also corrects specific errors concerning qiyās, Naṣīr al-Dīn al-Ṭūsī’s death date, and the alleged beginning of systematic Shiʿi theology with the Tajrīd al-iʿtiqād. It concludes that encyclopaedic authority should not obscure authorial situatedness, diachronic discontinuity, or methodological plurality.