Detailed descriptions of our methodology compound library are presented elsewhere (Akers, Severson, Andrews, & Lichtenstein, 2007; Lichtenstein et al., 2002; Severson et al., 2000, 2007). Baseline characteristics of participants and their partners The 328 male participants in this secondary analysis had a mean age of 41.6 years (SD=11.5), 94.8% had at least a high school education (34.4% completed college), and they used an average of 3.7 tins or pouches of smokeless tobacco per week (SD=2.27). Their partners had similar age (M=41.1 years, SD=10.1) and education (40.2% completed college), and on average, they had been together for more than 15.6 years (SD=11.5). No partners used smokeless tobacco, although 12.5% were smokers. Measures Outcome measures.

Tobacco abstinence was measured using 7-day point prevalence self-report measures at 6 and 12 months as well as by repeated point prevalence (considering abstinence at both 6 and 12 months). Happiness in relationship and support for quitting. The partner baseline assessment included Item 31 from the Dyadic Adjustment Scale (DAS; Spanier, 1976) that asked, ����indicate the degree of happiness, all things considered, of your relationship,�� using a 7-point scale (0=extremely unhappy, 1=fairly unhappy, 2=a little unhappy, 3=happy, 4=very happy, 5=extremely happy, and 6=perfect). Goodwin (1992) reported that DAS Item 31 could be used to differentiate between adjusted and distressed couples as indicated by total DAS. Moreover, the item has been incorporated in the four-item version of the Couples Satisfaction Index, for which psychometric properties have been reported by Funk and Rogge (2007).

Another baseline item asked partners, ��How much do you want him to quit chewing or dipping?�� (1=not at all, 4=somewhat, and 7=very much). Partner positive and negative support. At their 6-week assessment, partners reported how often they delivered support for quitting smokeless tobacco to their male companion, and study participants rated the frequency of smokeless tobacco quitting support they received from their female partner. The 6-week assessment occurred after tobacco cessation materials had been distributed to assess the effects of support during the initial stage of quitting. Measures of support were derived from the self-report Dacomitinib Partner Interaction Questionnaire (Cohen & Lichtenstein, 1990; Roski, Schmid, & Lando, 1996) that had been adapted for smokeless tobacco (cf. Lichtenstein et al., 2002).