This introductory guide to college instruction is intended for graduate students who are or are to become teaching assistants (TAs). It proposes that TA effectiveness may be improved through self-reflection, information about teaching, and adjustments in teaching practices. The first three chapters are introductory. The first considers teaching assistantships from historical and contemporary perspectives and describes the benefits and challenges of the system. Chapter 2 examines the process through which graduate students try out and become comfortable with varying teaching roles and find a teaching style that is both comfortable and effective. The third chapter considers the problems TAs face as they seek to relate to students, course directors, and support staff members. The remaining chapters look at areas of competence all successful TAs must master, including: skills for effective instructional planning; creating a positive classroom atmosphere; making lectures and other class presentations interesting and relevant; conducting productive class discussions; conducting autonomous skill development courses, teaching individuals, and laboratory sections; measuring and evaluating student progress; and external and self-assessment. (Author/MSE)