This article first describes some general criteria that can be applied to the development of any type of learning materials. Second, the article lists criteria for creating CLIL (content and language integrated learning)-specific learning materials, and provides examples of how to apply each proposed criterion whilst also providing a corresponding rationale with references. Third, additional requirements pertaining, among others, to technical, environmental and social issues that apply equally to CLIL and non-CLIL materials are presented. This article aims to serve as a practical tool for CLIL materials development, hence it uses an atypical format and structure. (Contains 19 footnotes.)