This report provides insights into my three months internship at the World Council of Churches in Geneva. The objective was to create a toolkit for the congregations about sustainable practices from churches worldwide. Firstly, I explain the framework of the internship, the circumstances, the workload, and the outputs. Secondly, I provide more detailed information about the context of action (the toolkit) and elaborate why the organization works in the sustainability sector and why there is a need to create a toolkit for the congregations. In my third point, I give an introduction to the structure and organization of the World Council of Churches, including the different areas of work, the duties, etc., followed by a stakeholder analysis in the fourth point. Afterward, some insights on the financial resources of the WCC are provided, before I start to introduce my main work during the duration of the internship, the toolkit. The document is split into three sections, whereby I discuss every section and provide key practices and resources mentioned in the toolkit, but also give foresight to the next steps of this document. In the last two points, I provide my very own opinion about the internship and offer some criticism and suggestions to the Economic and Ecological Justice Department of the World Council of Churches, by considering the limits I observed and the challenges I faced. I conclude with a summary of the previous points and a final statement.