The HUMAINT winter school is conceived as an interdisciplinary course about the impact of Artificial Intelligence (AI) systems on human behaviour. After a successful first event, this year edition focuses on the topic of fairness and accountability in AI and it is taking place one week before the ACM Conference on Fairness, Accountability, and Transparency (ACM FAT*), a computer science conference with a cross-disciplinary focus that brings together researchers and practitioners interested in fairness, accountability, and transparency in socio-technical systems.