One of the NijCa²re lines of research focuses on the treatment of anxiety disorders. These so-called treatment studies mainly take the format of randomised clinical trials (RCTs). In an RCT the efficacy of an experimental protocol is compared with another treatment where participants are randomly (arbitrarily) assigned to one of the two treatment arms. As an illustration, in one such RCT we are examining whether an intensive outpatient treatment protocol for posttraumatic stress disorder (PTSD) in which all sessions are delivered within five weekdays yields faster and better results than a standard PTSD protocol where sessions are scheduled across a 12-week period. At study conclusion, we will then be able to conclude whether the two treatments are equally effective or whether one treatment produces superior outcomes. In our research of anxiety disorders we are also curious to identify outcome predictors, i.e. factors that predict successful treatment outcome. At NijCa²re we are, for instance, in the process of investigating whether in PTSD a patient’s response to exposure predicts treatment success.