In this paper we discuss the general approach and choices we made in developing a prototype of a social media monitor. The main goal of the museum monitor is to offer museum professionals and researchers better insight in the effects of their own social media usage and compare this with other actors in the cultural heritage sector. It gives researchers the opportunity to consider communication within the sector as whole. In the research project “Museum Compass” we have developed a prototype of a social media monitor, which contains data of current and historic online activities on Facebook, Twitter, YouTube, Foursquare and Flickr of all registered Dutch museums. We discuss – mostly in a practical sense – our approach for developing the monitor and give a few examples as a result of its usage.