This chapter explains common practices and customs at the CNS drug trial site, a complex ingredient in the recipe for new medicines. The organization diagram of most trial sites is simple. The critical ingredients are the principal investigator and the clinical coordinators. Investigators conduct CNS clinical trials in diverse local settings, various size businesses, and different national cultures. Success depends on the talents of people with various backgrounds, training, and experience. Doctors prescribe for patients who live in many different environments; therefore, research settings parallel the clinic setting where patients are likely to take the medicines. FDA demands the investigator assign trial roles and train the staff. Repeat business from satisfied sponsors is not only the benchmark of success, but research sites perform best when they pick up a drug early and stay with it throughout the product life cycle.