Behavioral Support for Abstinence was the proportion of people in the network who were abstinent. Attitudinal Support for abstinence was calculated by taking the mean of the reactions to not drinking of the top four persons on the participant's list of important people (with reactions scaled from 1 = “left the room” to 5 = “encouraged” non-drinking). Internal reliability of Attitudinal Support for Abstinence at all follow-ups exceeded alpha = .66. An additional variable, Number of Abstinent Friends in the Social Network, was the number of nondrinking persons in the social network that the respondent interacted with at least once per week. The intercorrelations of the network support variables were in the range of .2 to .6 (except for the correlation of Behavioral Support for Abstinence with Number of Abstinent Friends, which correlated at r = .8), indicating that these variables represented related, but not redundant, constructs.
