Objective: Communities Mobilizing for Change on Alcohol (CMCA) was a random
ized 15-community trial of a community organizing intervention designed to
reduce the accessibility of alcoholic beverages to youths under the legal d
rinking age. Method: Data were collected at baseline before random assignme
nt of communities to intervention or control condition, and again at follow
-up after a 2.5-year intervention. Data collection included in-school surve
ys of twelfth graders, telephone surveys of 18- to 20-year-olds and alcohol
merchants, and direct testing of the propensity of alcohol outlets to sell
to young buyers. Analyses were based on mixed-model regression, used the c
ommunity as the unit of assignment, took into account the nesting of indivi
dual respondents or alcohol outlets within each community, and controlled f
or relevant covariates. Results: Results show that the CMCA intervention si
gnificantly and favorably affected both the behavior of 18- to 20-year-olds
(effect size = 0.76, p < .01) and the practices of on-sale alcohol establi
shments (effect size = 1.18, p < .05), may have favorably affected the prac
tices of off-sale alcohol establishments (effect size = 0.32, p = .08), but
had little effect on younger adolescents. Alcohol merchants appear to have
increased age identification checking and reduced propensity to sell to mi
ners. Eighteen- to 20-year-olds reduced their propensity to provide alcohol
to other teens and were less likely to try to buy alcohol, drink in a bar
or consume alcohol. Conclusions: Community organizing is a useful intervent
ion approach for mobilizing communities for institutional and policy change
to improve the health of the population.