One of the most prominent Muslim scholars and scientists of the medieval era, the Persian polymath Naṣīr al-Dīn Ṭūsī (1201-1274) joined the Shi‘a Nizari Ismaili community at a young age, as the armies of Genghis Khan poured across his homeland. In the course of a long and eminent career, first under the patronage of the Ismailis at the fortress of Alamut, and later with the conquering Mongols, he produced over 150 works on diverse subjects from theology and philosophy to mathematics and astronomy. His principal works on Ismaili doctrine, the Rawḍā-yi taslīm (The Paradise of Submission) and the autobiographical Sayr wa sulūk (Contemplation and Action), are already available in English translation by S J Badakhchani. In this volume, he offers new critical editions and translations of three shorter Ismaili works by Ṭūsī, namely Aghaz wa anjam (The Beginning and the End), Tawallā wa tabarrā (Solidarity and Dissociation), and Maṭlūb al-muʾminīn (Desideratum of the Faithful). In these three treatises, Ṭūsī provides concise interpretations of key motifs in Ismaili doctrine, with special reference to the primordial nature of man, his earthly existence in relation to the imam, and his destiny in the hereafter.