Functional assessment and functional analysis are processes that have been applied successfully in work with people who have developmental disabilities, but they have been used rarely with students who experience emotional or behavioral disorders. In the present study, five students in elementary school programs for severe emotional disturbance participated in a comprehensive functional assessment process designed to yield a useful understanding of their desirable and undesirable behaviors. Interviews, record reviews, and direct classroom observations led to the development of individualized hypotheses regarding relationships between classroom events and the occurrence of target behaviors. Subsequently, direct manipulations (i.e., functional analyses) were conducted to test each of the hypotheses in the context of regularly-occurring classroom activities. These analyses demonstrate important influences that certain classroom variables can exert over individual student's behavior. The process and results are discussed with regard to the need for improved methods for understanding student responding, and the benefits that functional assessment can offer programs of educational and behavioral support. [This is the third in a series of three classic article reprints celebrating the rich history of impactful scholarship published in Behavioral Disorders in the 1970s, 1980s, and 1990s. For the original, "Functional Analysis of Classroom Variables for Students with Emotional and Behavioral Disorders," see EJ470666.]