Testing the hypothesis that socioeconomic status (SES) is related to altruistic behavior, 466 respondents derived from 4,799 households in rural Western Colorado (Woodland Park, Gunnison City, and Durango) were contacted to determine the degree of voluntary basement sharing that might be expected in the event of a nuclear crisis. Respondents were divided into 4 groups; wherein, groups 1 and 2 (2,117 and 1,378 respondents) were contacted via minimum and extended mail only, the interview group was contacted by interview and mail (N=241), and the control group (N=543) by mail only. A mass media program preceded the personal contacts and employed social-psychological techniques. The SES variables employed were occupation, educational attainment, and age. Results indicated: occupation, educational attainment, and age were all significantly associated with altruistic behavior as measured by willingness to share; occupation was not related to sharing under any situation where age and education were controlled; age was related to altruism when there was a combination of high or low education and occupation; education was related to sharing with high occupation and middle age or with low occupation and other age. Study limitations were a sample including only basement owners and the possibility of nonrelated and/or limited SES variables. (JC)