This chapter considers attribution in the law of State responsibility for conduct involving the use of autonomous cyber capabilities (ACCs). It consist of four sections. The first section provides an overview of ACCs and the concerns they raise when used by States in cyber operations. The second section outlines the general rules on State responsibility as detailed in the in the International Law Commission’s Articles on the Responsibility of States for Internationally Wrongful Acts, and in the Tallinn Manual 2.0 on the International Law Applicable to Cyber Operations. Section three then examines the rules surrounding attribution and their application to conduct involving the use of ACCs, and the extent to which autonomy problematizes these rules. Finally, section four considers the application of these rules in a possible future scenario where States have given software entities a degree of legal personality, and it examines the extent to which this status can be used to avoid responsibility for the actions of ACCs. This chapter concludes that, while there are challenges to attributing cyber operations generally, the technical autonomy of ACCs ultimately does not change how the law applies and imposes obligations on the State and its human agents in their use of ACCs. Further, even where software agents were given a degree of legal personality, the link between these entities and the human beings responsible for their creation is sufficient to establish attribution under the law on State responsibility.