Graduate and first-professional students form a diverse group. In 1999–2000, some notable differences in student characteristics, enrollment patterns, and methods of paying for postbaccalaureate education existed across the major program levels (master’s, doctoral, and first-professional), but differences existed within levels as well.

About one in five graduate and first-professional students had a teaching or research assistantship in 1999–2000, but assistantships were more common at the doctoral than at the master’s or first-professional levels. Assistantships were also concentrated by field. About three-quarters of doctoral students in science and in engineering received assistantships, and they received larger amounts on average than those in the humanities/social sciences. Teaching assistants spent an average of 15 hours per week working with students in the classroom or lab, holding office hours, or assisting faculty with grading or other instruction-related tasks.