The Mongols' relationship with the Ismâ'îlîs or Assassins has generally been considered in terms of their destruction of the Ismâ'îlî power in Northern Iran under Hülegü. While this was certainly the denouement of their relationship, the Mongols and the so-called Assassins have a much longer common history. Indeed, they often shared mutual enemies in the person of the Khwarazmshah Muhammad, and then of his son, Jalâl al-Dîn. This article, thus, examines the pattern of the Mongol-Ismâ'îlî relationship from their first contact to the severing of ties, and discusses whether the Mongols established an alliance with the Assassins.