This is a White Book created by GREENGAGE Consortium. It presents lessons learned from GREENGAGE activities and make recommendations for public authorities on setting up and createing a Citizen Observatory. It focuses on various dimensions which can play critical role in designing and managing Citizen Observatories, and it shares Lessons and Recommendations that were collected based on the experience from 5 GREENGAGE city pilots. "GREENGAGE_WhiteBook.pdf" is an interactive document. "GREENGAGE_WhiteBook-booklet print.pdf" is prepared for printing it as a booklet. In the printing settings set as: landscape, double sided, left binded. "GREENGAGE_COExample-NorthBrabant.pdf" is an addition to the White Book. It's a document presenting an example from one of the GREENGAGE pilots - North Brabant.