Cos4Cloud is developing thirteen technological services focused on boosting citizen science observatories to help increase and improve the quantity and quality of observations. The project includes the participation of 9 established citizen observatories (CO) and Do it Yourself (DIY) initiatives, focused on biodiversity and the environment, integrating and testing these services. Part of this also, are capacity building, training, educational, networking, dissemination, codesign, communication and engagement collaborative strategic actions and initiatives which also demonstrate Cos4Cloud best practice. Facilitating networking and citizen science knowledge management processes across organisations, people and initiatives is one of the key objectives of the Cos4Cloud project. Task 6.5 Training and Capacity building services, part of Work Package 6 (WP6) ‘Networking, Training [Education] and Capacity Building’, supports this. Task 6.5 focuses on actions and initiatives for training citizen observatories participants, managers / leaders, developers and other potential target groups and stakeholders about the use of Cos4Cloud services. The development and validation of user / administrator / system guides and handbooks for different services, shared via the Cos4Cloud Toolbox and Evidence Hub is included as part of this. This deliverable demonstrates the training materials and resources being developed to be made available online, as part of the Toolbox; outlines the capacity building framework guiding the development of these materials and reports on how they will be made accessible. This D6.6 Training materials and Capacity Building Report: Introduces capacity building and citizen science and proposes and approach of adapted to Cos4Cloud Summarises some of the research conducted which influences and defines the model and framework Includes an outline of other Cos4Cloud approaches and strategies supporting this Outlines the training and capacity building plan, supporting the Cos4Cloud services in particular, under implementation as part of the model devised for the Toolbox and Evidence Hub Includes summary examples of the training materials and resources developed supporting the Cos4Cloud services which will be live and accessible from the Cos4Cloud Toolbox and Evidence Hub before the end of the project; and Concludes with a summary of development and next steps for implementation and sustainability strategies supporting this which will help to build a legacy for Cos4Cloud in the citizen science landscape and the European Open Science Cloud (EOSC) beyond the lifetime of the project.