**Background:** Adolescent and young adult solitary drinking is a risky behavior prospectively associated with alcohol problems, including alcohol use disorder symptoms. Prior research consistently links solitary drinking to drinking to cope motives (i.e., drinking to alleviate negative affect), but all prior studies assessed general drinking motives without specifying the drinking context. This study is the first to directly compare solitary-specific coping motives with general coping motives in predicting solitary drinking behavior and alcohol problems.
**Methods:** Participants were 307 current underage drinkers (ages 18–20; M_age = 19.28, SD = 0.76; 89.90% female; 69.38% Caucasian) recruited from an Amazon TurkPrime panel (March–May 2016) who endorsed any solitary drinking in the past year. Participants completed online surveys assessing: solitary alcohol use (percentage of drinking time spent alone), general drinking motives (DMQ-R coping α = 0.87, enhancement α = 0.86), solitary-specific drinking motives (adapted DMQ-R coping α = 0.90, enhancement α = 0.87), and alcohol problems (B-YAACQ α = 0.91). Separate linear regression models compared solitary-specific vs. general coping motives in predicting solitary drinking and alcohol problems, controlling for demographics and enhancement motives. Models predicting alcohol problems also controlled for drinking quantity, frequency, and solitary drinking percentage.
**Key Results:** Mean solitary drinking was 32.15% (SD = 27.31) of total drinking time. Solitary-specific coping motives were positively associated with percentage of time spent drinking alone (β = 0.26, p < 0.001) after controlling for demographics and solitary-specific enhancement motives (Model 1: R² = 0.08, F(6,299) = 5.57, p < 0.001). General coping motives were also positively associated with solitary drinking (β = 0.23, p < 0.001), but general enhancement motives were negatively associated (β = -0.13, p < 0.05) (Model 2: R² = 0.03, F(6,300) = 2.57, p < 0.02). The solitary-specific motives model accounted for greater variance (adjusted R² = 0.08 vs. 0.03). For alcohol problems, solitary-specific coping motives were positively associated (β = 0.31, p < 0.001) controlling for demographics, solitary drinking percentage, solitary enhancement motives, and drinking frequency/quantity (Model 3: R² = 0.40, F(9,296) = 23.42, p < 0.001). General coping motives showed a stronger association (β = 0.40, p < 0.001) and the model accounted for greater variance (Model 4: R² = 0.49, F(9,297) = 33.59, p < 0.001).
**Clinical Implications:** Solitary-specific coping motives provide additional predictive utility for solitary drinking behavior beyond general coping motives, supporting theoretical models that emphasize negative reinforcement as the primary driver of drinking alone. However, general coping motives are sufficient for predicting alcohol problems, suggesting interventions should target drinking to cope with negative affect regardless of drinking context. Clinicians may use solitary drinking as an easily observable screening indicator for risky alcohol use, as it can be assessed with a simple yes/no question. The study is limited by its cross-sectional design, predominantly female and White sample, and restriction to participants who endorsed any solitary drinking, which may have reduced variance in some associations.