Gambling and alcohol use disorders commonly co-occur. Nationally representative samples suggest that 45% to 73% of pathological gamblers have lifetime alcohol use disorders (Cunningham-Williams, Cottler, Compton, & Spitznagel, 1998; Petry, Stinson, & Grant, 2005). Among treatment-seeking pathological gamblers, comorbidity is also high, with 59% reporting lifetime histories of alcohol use disorders (Kausch, 2003). Despite the high comorbidity rates of these disorders, few studies have examined if drinking changes during gambling treatment. Not only are gambling and substance use disorders frequently comorbid (Kessler et al., 2008), but the behaviors tend to co-occur. Among non-pathological gamblers, up to 80% reported consumption of 4 to10 alcohol drinks during their last gambling episode (Baron & Dickerson, 1999), and those who drank while gambling tended to gamble in more risky ways and experienced more negative consequences of gambling (Cronce & Corbin, 2010; Giacopassi, Stitt, V National Institute of Alcohol Abuse and Alcoholism [NIAAA], 2007). At-risk drinking rates are also high among individuals with gambling problems. Abbott, Williams, and Volberg (2004) reported 40% to 54% of problem and pathological gamblers identified in a community survey engaged in risky drinking, and Smith and colleagues (2010) estimated 31% of treatment-seeking gamblers were risky drinkers. The high rates of drinking among non-pathological gamblers (Baron & Dickerson, 1999) as well as among individuals who have developed gambling-related problems (Abbott et al., 2004; Smith et al., 2010) are concerning given that quantity of alcohol use appears to be related to severity of gambling problems. In a large statewide survey, Blankenship, Starling, Woodall, and May (2007) found that gamblers reporting 3 or more alcohol drinks per occasion were more likely to endorse problem gambling behaviors than those who consumed 1 or 2 drinks per occasion. Using national epidemiological data, French, MacLean, and Ettner (2008) also found an association between severity of gambling problems and alcohol consumption, with the strength of the relationship increasing as alcohol use increased. In addition, Abbott et al. (2004) reported that hazardous alcohol use predicted continued difficulties with gambling over a 7-year period among individuals with problem and pathological gambling. With repeated pairings of the behaviors, gambling situations may become conditioned cues for drinking. In a laboratory study, Stewart and colleagues (2002) found that participants randomized to a condition in which they could gamble were more likely to purchase and consume alcoholic drinks than participants randomized to a non-gambling control activity. Those who drank alcohol during the laboratory gambling situation reported histories of more frequent gambling, more years gambling, and more gambling-related problems compared to those who did not consume any alcohol when randomized to the laboratory gambling situation. A study by Zack and colleagues (2005) examined implicit associations between gambling and alcohol. The results suggested that positive gambling words (i.e., winning) activated alcohol-related semantic networks for gamblers who reported drinking in response to gambling wins, and that this association was stronger for those with more severe alcohol problems. If gambling becomes a conditioned cue for alcohol use as these studies suggest, then the absence of, or a reduction in, gambling during the course of gambling treatment may result in lower drinking as well. Theoretical conceptualizations of behavior change can also be useful in explaining why two behaviors, such as alcohol use and gambling, may decrease in close temporal proximity. The decision to seek treatment for one problem behavior may spur thinking about changes in other domains. Hall and Rossi (2008) found a high degree of similarity in decision-to-change processes across 48 health behaviors. This similarity in decision processes may facilitate the spread of change to other behaviors recognized as unhealthy once primary behavior change begins. Noar and colleagues (2008) frame these changes using a hierarchical model of health behavior attitudes and behaviors. Attitudes toward change of multiple health behaviors are united under a global construct of general health orientation. In this model, change in the higher-order health behavior orientation (e.g., “I need to be more healthy”) may produce multiple individual health behavior attitude changes (e.g., “I need to change smoking, gambling, and alcohol use”) that in turn cascade down to changes in attitudes toward specific behaviors (e.g., “I should stop smoking, only gamble moderately, and stop at two drinks”). These specific attitudes may ultimately produce change in their respective behaviors. Although treatment-seeking gamblers may present to treatment for gambling, they may also be open to changes in multiple health behavior attitude domains, as driven by the higher-order health orientation construct. A contrasting perspective is that of symptom substitution. A concern during the treatment of addictions (Kadden, Litt, Kabela-Cormier, & Petry, 2009), symptom substitution involves switching one substance for another during treatment. Given the strong associations between alcohol and gambling highlighted above, and behavioral and biological similarities across addictive disorders (Petry, 2006, 2007a; Potenza, 2006; Shaffer et al., 2004), symptom substitution (increased alcohol use while attempting to decrease gambling) is a viable hypothesis. Two studies (Toneatto, Skinner, & Dragonetti, 2002; Stinchfield, Kushner, & Winters, 2005) examined the percent of pathological gamblers who drank before and after gambling treatment. Toneatto et al. (2002) found similar rates of self-reported past-month alcohol use (yes/no) at study intake (55.4%) and at a 1 year follow-up (50.6%). Stinchfield and colleagues (2005) categorized treatment-seeking pathological gamblers as never, less than monthly, monthly, weekly, and daily drinkers at baseline and at a 6-month follow-up. Participants evidenced lower drinking levels between baseline and post-treatment follow-up, with the greatest reduction occurring in the initially highest frequency drinkers (e.g., 54% moved from weekly or daily drinking to monthly or less drinking). These results (Toneatto et al., 2002; Stinchfield et al., 2005) do not support symptom substitution, but neither study examined alcohol use during the treatment period. The lack of during treatment assessment of alcohol use limits our ability to understand drinking behavior during gambling treatment, as alcohol use can fluctuate greatly between pre- and post-treatment periods. Additionally, although the Stinchfield et al. (2005) study noted drinking frequency reductions following gambling treatment, neither study examined quantity of alcohol use. Given that many gamblers drink at binge levels (Abbott et al., 2004; Baron & Dickerson, 1999; Smith et al., 2010) and that two large-scale studies identified associations between problem gambling and quantity of alcohol consumed (Blankenship et al., 2007; French et al., 2008), studies that examine drinking quantity may provide a more detailed picture of changes in alcohol use among individuals seeking gambling treatment. The present study used longitudinal data of drinking behavior over 36 weeks to understand more fully the drinking patterns among treatment-seeking pathological gamblers. We assessed drinking behavior prior to treatment (12 weeks), during treatment (12 weeks), and following gambling treatment (12 weeks). Using weekly estimates of drinking quantity (in standard drinks per week), this study provides a more dynamic and thorough view of drinking behavior in relation to gambling treatment relative to prior studies. Given initial results from the Toneatto et al. (2002) and Stinchfield et al (2005) studies, we hypothesized that drinking behavior for the overall sample would remain the same or decrease during gambling treatment.