This document provides methodological and practical guidelines (incl. a common reporting template) for case study (CS) implementation, which are closely connected to previous, ongoing and future WP components (WP1, WP2, WP3, WP4, WP5). At the core of CS implementation is the process model underlying the analytical framework D2.4. and the resulting standardized CS reporting as outlined below. The mixed-methods approach implemented in MATS is to be adapted to the specific CS context, while a meaningful grouping of methods, tools and indicators across case studies contributes to comparability and cross-case consistency, and thus the overall systemic approach of MATS. The cases work jointly toward an overarching transition pathway (WP5), by developing individual impact pathways, while allowing for customized case-relevant assessments and coverage of additional sustainability indicators beyond core indicators uniting all cases. To translate these requirements into practice, the aim of D3.1. is to provide guidance for the implementation and standardized reporting of the case studies, and to ensure scientific value added over single case study methods approach and single case implementation. This value added is achieved when D3.1. is implemented in line with the analytical framework D2.4., which lays out the overarching inter-disciplinary methods framework and links to D3.1. through identical case implementation steps (Figure 4, D2.4.). The analytical framework D2.4. is thereby to be consulted in conjunction with D3.1., also to retain the connection between CS individual pathways and the overall impact pathway (connecting D2.2, D3.1 and WPs 4 & 5). At the practical level, the anticipated scientific value added is also expected to be achieved through mutual learning in a recursive and constantly updating process of case study implementation (joint workshops and zoom information sessions), and by obtaining methods synergies from group-wise CS implementation (groups of CS implementing the same methods approach, and same core sustainability indicators; learning from limitations and strengths of methods application; synergies from effective data exchange and data use across CSs and WPs), yet also achieved by making it explicit during CS implementation and in CS reporting which biases have been encountered and how they have been addressed in implementing the case studies. The case studies are implemented in the period 1.7.2022 – 30.1.2024. A first draft report is to be submitted by 30.6.2023 for internal feedback. The final CS report is due 30.1.2024. The two broad key questions for the 15 CSs in MATS are: How do trade regimes, investments (esp. into agri-food value chains) and sustainability standards impact local, and, in some cases, national, and international socioeconomic and environmental conditions? and How to foster the positive and reduce the negative impacts of agri-food trade and trade policy regimes on sustainable development and human rights? In the implementation of CS, CS leads need to ensure that, data management is compliant with the EU’s Guidelines on Findable, Accessible, Interoperable and Reusable (FAIR) Data Management in Horizon 2020; all personal data are treated as strictly confidential and processed in compliance with General Data Protection Regulation 2016/679; anonymized data from surveys and interviews will be securely stored in a safe location at partners' facilities (internally, anonymized data may be shared) (see also the D7.4 ‘Data Management Plan’ and Ds 8.1-8.3 ‘Ethical Requirements’ on MS Teams); the identity of actors and researchers in case reporting is anonymized where this is deemed relevant to protect CS participants and researchers.