The School of Management (SOM) at Union Graduate College (UGC) used student trajectories to forecast both individual course and total enrollments within and across various student categories. (The term "trajectory" refers to the enrollment pattern of the average student in a particular category.) The trajectories and the resultant projections formed an integral part of diagnostic tools for enrollment management decision-making, short- and long-term course section planning, and faculty capacity analyses in a variety of scenarios to inform program development, program promotion, and faculty hiring, and to make sure they were consistent with each other. This article describes the concepts behind trajectories, various types of trajectories and their respective uses, details for constructing trajectories, and how trajectories can be incorporated in reports and tools for maximum utility.