Since 1984, the International Workshop on Nonmonotonic Reasoning (NMR) is the premier venue for presenting and discussing current results in the area of Nonmonotonic Reasoning. It brings together researchers interested in various aspects of knowledge representation and reasoning (KR), including belief revision, uncertain reasoning, reasoning about actions, planning, logic programming, preferences, argumentation, causality, and many other related topics including systems and applications.

This volume serves as the informal proceedings of NMR 2024 held on November 2-4, 2024, in Hanoi, Vietnam. The programme of the Workshop featured presentations on a wide range of topics, among them: answer set programming, argumentation theory, belief change, cognitive aspects of nonmonotonic reasoning, and conditional logics. Each submission was thoroughly peer reviewed. We would like to express sincere thanks to the programme committee members for their effort-it not only helped the selection of the best papers, but also improved their quality through the generous feedback offered to the authors. Out of 25 submissions, the committee decided to accept 19 full papers (of which 1 was consecutively withdrawn) and 1 extended abstract. As a result, 19 papers were presented at the Workshop. Moreover, the programme had one session in common with the Joint Workshop on Knowledge Diversity and Cognitive Aspects of KR, which featured two interesting talks. We are very grateful to Richard Booth (Cardiff University, United Kingdom) and Sarah Alice Gaggl (TU Dresden, Germany) for contributing very inspiring invited lectures.

NMR 2024 was co-located with the 21st International Conference on Principles of Knowledge Representation and Reasoning (KR 2024). We thank the organizers of the KR 2024 conference for their excellent support. Finally, let us express our gratitude to the generous sponsors of NMR 2024: Artificial Intelligence Journal and KR Inc. (Principles of Knowledge Representation and Reasoning).

We hope that this workshop will be inspiring to the participants and that it will foster new collaborations.