To determine the prevalence of drug abuse in city neighborhoods in a developing country undergoing rapid urbanization, we performed a household survey on the spread of drug abuse in Vientiane, Lao People's Democratic Republic. A total of 1497 households from 17 villages were selected by the stratified random sampling method from urban districts in the city of Vientiane. Participatory style research was employed to increase both the sensitivity of detection and the reliability of information gathered. Local key players shared in the participatory process in this study. We worked with national and city officers and community leaders, as well as with neighborhood leaders who had received previous training for this survey, and conducted household surveys using face-to-face interviews. We inquired about the spread of drug abuse by asking if the families interviewed recognized drug abuse problems in their community. To examine the extent of urbanization of individual villages, the urban index was calculated by principle component analysis from the following eight indicators: income, occupation, parents' educational histories, diffusion of telephones, ownership of livestock, diffusion of plumbing for running water and distance from the Vientiane city center to the village. Distance was calculated by the Geographic Information System. Among the 17 villages included in the study, the average percentage of recognition of drug abuse in the community was 63.2%. The relationship between recognition of cases of drug abuse in the community and the urban index showed a significant correlation, with a Spearman coefficient of 0.650 (p < 0.01). The high reliability of participatory style surveys is also discussed. In conclusion, city neighborhoods in a developing country undergoing rapid urbanization showed evidence of the spread of drug abuse, which was associated with the urban index. Participatory style research activity was recommended to help raise awareness of community participation in anti-drug-abuse activities.