This paper revisits the concept of trajectory, as set out by Glaser and Strauss in 1965 and developed by others. Much of the research utilizing this concept has been focused on illness and the organization of work and biographies of participants involved in managing illness trajectories. The emphasis of this paper is not illness, but clinical trial research. It utilizes the concept of trajectory as a lens for this empirically grounded thick description of the occupational personnel and the work activities of clinical trials research. It draws on data collected in an ethnographic field study of informed consent and AIDS clinical trials. Social scientists and clinicians are involved in the implementation of clinical trials and in the transfer and utilization of knowledge and interventions derived there from. Therefore, this paper seeks to contribute to scholarship on this complex field of practice.