The Landscape Report on Diamond Open Access Publishing in Africa, Europe, and Latin America provides a comprehensive overview of the Diamond Open Access (OA) publishing ecosystem across 45 countries in Africa, Europe, and Latin America. The main objective of the report is to describe the systemic conditions and public policies that surround the development of the Diamond OA scholarly publishing model in each country, followed by an analysis of each of the three world regions. The country-level analysis includes a review of legal frameworks, specific policies, funding mechanisms, incentives and recognition systems, digital infrastructures and platforms, institutional support, human resources, the collaboration mechanisms between publishing services and editorial service providers, and editorial quality certification mechanisms. In addition, it includes a set of actions required to develop and strengthen national Diamond OA scholarly publishing systems. The report highlights both the unique characteristics of each country and the diversity across regions, while also identifying shared patterns. First, it reveals significant variation in the existence, maturity, and scope of policies supporting Diamond OA publishing, alongside a general absence of structural funding. Second, it underscores the critical role of platforms, regional portals, and supporting digital infrastructures, despite differing levels of maturity and robustness function as key infrastructures for improving the quality and visibility of the Diamond OA model. Finally, the report shows that Diamond OA scholarly publishing suffers from a strong dependence on volunteer labour that is often unrecognised and unrewarded. Combined with the absence of academic incentives for publishing in or managing Diamond OA journals, this situation creates weaknesses in the continuity, quality, and scalability of the model in most of the analysed ecosystems. The report provides a set of recommendations addressed to policymakers, institutions, research funding agencies, non-profit editorial teams, and libraries. The Landscape Report on Diamond Open Access Publishing in Africa, Europe, and Latin America is Deliverable D4.1 of the EU-funded ALMASI project (Aligning and Mutualizing Nonprofit Open Access Publishing Services Internationally), under Grant Agreement ID 101188192.