This chapter reviews Zaydī theology in Yemen, from the period before and after the unification of the Yemeni and the Caspian imamates to theologians from the ninth/fifteenth century. It traces the foundation of the Zaydī imamate in the northern highlands of Yemen by Imam al-Hādī ilā l-Ḥaqq, and how the Yemeni Zaydīs developed a canon of doctrinal writings of the Imams which remained authoritative over the coming centuries. It considers the role played by Jaʿfar b. Aḥmad b. ʿAbd al-Salām al-Buhlūlī in the intellectual development of Yemen’s theological landscape, as well as the legacy of al-Ḥasan b. Muḥammad b. al-Ḥasan al-Raṣṣāṣ with respect to Bahshamite theology in the country. It also examines the continuity of Bahshamite theology from the seventh/thirteenth century and concludes with a discussion of the emergence of growing opposition among the Zaydīs of Yemen against Muʿtazilism in general and the theological views of the Bahshamiyya in particular.