Characteristics of persons with autism and other developmental disabilities may make this population especially vulnerable to the effects of stress. Prior research on stress and its measurement in this population is reviewed. Using a single-case multi-element design, this study explores the feasibility of measuring cardiovascular responses to four stressors in 10 individuals (age 13 to 37 years) with autism and other developmental disabilities. Results suggest that assessing cardiovascular responses is a viable procedure for identifying individual differences in reactivity to specific environmental stressors. Implications of this research and future directions for assessment are discussed.