Observational studies examine the behaviour of building users in real-life settings. The purpose is to understand the reality of what people do as opposed to what they say they do in interviews and surveys. Observational studies can be done in different ways. The classic approach is to place an observer in a space who then registers the use of this space, making notes of how many people are there, what they are doing, and what kind of tools or artefacts they use. When working on a library project, it could be interesting to observe how reading rooms are being used. Are people actually reading books there, or are they mostly working on their computers? Is the room studiously quiet, or are people chatting? Are people moving around or staying put? Such observations can reveal a lot about the use and the purpose of a reading room, which may be different from what the name suggests.An alternative observation method is shadowing. With this method, a building user is followed around by an observer. The focus of shadowing is not so much on how people use a particular space, but on getting an understanding of peoples activities and space usage over time. When preparing the brief for a hospital project, it will be useful to tag along with a nurse for a full day to get to know his or her work processes and the related spatial needs. Next to these traditional observation methods, there are high-tech observational methods that make use of cameras, infrared-sensors, sound-sensors and GPS tracking. These tools do more or less the same as human observers, but they are less time consuming and they provide more accurate, real-time data. Not many projects will have sufficient resources for extensive observational studies. It is always useful, however, to spend at least a couple of hours in the clients building to take in the sounds, the people, the activities and the artefacts. Such an informal way of observing will not produce detailed data about use patterns, but it will give a feel for the everyday use of the current building, which is a good starting point for a briefing process. Recommendations-Think beforehand about the purpose and set-up of the observational study. What is the subject of the observation and what kind of insights should the observational study produce?-Communicate the purpose of the observational studies to the buildings users beforehand.-When using cameras or GPS-data in observational studies, make sure that there are no privacy issues. Where necessary, ask for peoples permission.-Mix observations with short interviews to get a better understanding of what and why people behave the way they do.-Make sure the observations take place during a representative period (e.g. not during holidays).