This entry explores the theories of causality defended by Muʿtazilī scholars. Within this framework, I have analysed different theories of causality that are defended within the school of Muʿtazila. Accordingly, the theories of causality among the Muʿtazilīs can be divided into two main categories: the naturalistic theory of causality and the antinaturalistic theory. According to the naturalistic theory of causality defended by scholars such as Muʿammar, al-Naẓẓām, al-Jāḥiẓ, and al-Kaʿbī, beings have fixed and established natures that determine their modes of action. The universe is governed by causal relations based on these natures. This theory was strongly criticized by some scholars from the Baṣrian branch of the school, especially by Abū ʿAli al-Jubbāʿī, Abū Ḥāshim, Qāḍī ʿAbd al-Jabbār, Ibn Mattawayh, and al-Nīsābūrī. According to them, accepting natural causes makes it impossible for the agent to act and for God to be sovereign over the universe. Therefore, they adopted a more moderate understanding of causality. This was based on the theories of generated actions (tawlīd), impetus (iʿtimād), and the divine actions (ʿādah). This understanding accepts the principle of causality at work in the universe and human action but stresses that it is not absolutely necessary. Moreover, God can intervene in how the physical world works if He wishes, and some events happen entirely in accordance with divine custom.