The second module of this learning programme seeks to connect Citizen Science (CS) with Citizen Observatories(CO) in the context of environmental protection, highlighting a central and key field of application of both. This is initially done by investigating the ways CS can serve as a tool in environmental protection. Later, the definition of COs is provided, and the main aspects and characteristics is analysed. Subsequently, the fields of application of COs and their relation to CS is examined. Finally, the most important COs in Europe are presented. Lastly, the necessity and value of monitoring biodiversity as one of the main fields of application of COs is analysed in the appendix. All the above are covered in the 2nd module's framework as to answer the following questions: ✓ How can CS contribute to environmental protection? ✓ What are Citizen Observatories? ✓ What are the main aspects and characteristics of Citizen Observatories? ✓ What are the fields of application for Citizen Observatories? ✓ What is the relation between Citizen Observatories and Citizen Science? ✓ What are the most important environmental Citizen Observatories in Europe? ✓ Why does monitoring biodiversity constitute a central focus of Citizen Science?