Experimental analysis of social stimuli has typically been restricted to the presence or absence of verbal attention. In the present study, an ABAB design was used to assess the influence of proximity as a social stimulus. Close and distant proximity of a familiar adult was systematically manipulated to evaluate the effect of proximity on the on-task behavior of a 15-year-old male with autism. Baseline, experimental analysis, and intervention phases were conducted within a self-contained classroom. Pronounced effects of distant educator proximity to the participant were evident during both the experimental analysis and intervention, with increased on-task behavior occurring in the distant condition. Future recommendations for the investigation of proximity as a relevant social stimulus are forwarded. (Contains 1 figure.)