The role of social factors in pathological gambling has received relatively little systematic research. The goal of the current study was to examine the relationship between a target individual’s gambling behavior and the gambling behavior among that individual’s parents, siblings and five closest friends. The specific aims were, first, to apply a novel brief assessment to study the social density of factors relating to pathological gambling; second, to replicate previously observed findings involving the social aggregation of alcohol and tobacco use; and third, to examine social density findings among the three domains. Participants were 128 frequent gamblers from the Athens, Georgia area, 79.7 % male with a mean age of 34.2 (SD = 11.7). Participants were assessed using the Diagnostic Interview for Gambling Severity for gambling severity, the Alcohol Use Disorders Identification Test for alcohol abuse, the Fagerstrom Test of Nicotine Dependence for tobacco use, and the novel Brief Social Density of Gambling, Alcohol, and Tobacco Assessment. Significant relationships were observed between participants’ and friends’ activity within all domains: gambling (ps = .001), alcohol use (p < .001) and tobacco use (p < .001). Relationships with friends’ activity across domains were less strong. Distinct patterns of associations with parents and siblings were not observed. Thus, social aggregation was observed across the three domains of potentially addictive behaviors, generally with specificity within domains and with friends, not biological relatives. Methodological considerations and potential applications of these findings are discussed.