Descriptive and experimental analyses suggested that the self-injurious behavior (SIB) of a 10-year-old girl with severe mental retardation was maintained by attention. Additional analyses identified physical contact as the type of attention maintaining SIB; therefore, we hypothesized that physical proximity of an adult was a discriminative stimulus for SIB. Based on these findings, we systematically varied the distance between the participant and a therapist to assess stimulus generalization. Results showed that rates of SIB varied relative to the distance between the participant and therapist; the highest percentage of SIB occurred with the therapist positioned less than 0.5 m from the participant. Treatment consisted of placing the therapist at a specified distance (9.0 m) from the participant (during low-attention situations), noncontingent reinforcement, and extinction.