Electronic cigarettes (e-cigs) were created to approximate the look, feel, and experience of using a cigarette. Since cigarette and alcohol use co-occur, we hypothesized that e-cig and alcohol use also co-occur, likely due to shared positive drug expectations. Using self-report data from two independent samples of community-dwelling alcohol using adults, the present study: (1) modified the Nicotine and Other Substance Interaction Expectancy Questionnaire (NOSIE) to assess expectancies of combined e-cig and alcohol use (i.e. the individuals perceived likelihood of using e-cigs and alcohol together; NOSIE-ER); and (2) examined the relationships among e-cig use, expectancies, and alcohol use across e-cig use status. In the first sample (N = 692, mean age = 32.6, SD = 9.74, 50.7% female, 82.2% Caucasian), exploratory factor analysis suggested the presence of two factors: (1) alcohol use leads to e-cig use (Scale 1; α = 0.85); and (2) e-cig use leads to alcohol use (Scale 2; α = 0.91). In the second sample (N = 714, mean age = 34.1, SD = 10.89, 47.8% female, 75.6% Caucasian), confirmatory factor analysis supported this factor structure (χ2 = 47.00, p < 0.01, df = 19; RMSEA = 0.08, 90% CI = 0.05–0.11; TLI = 0.99; CFI = 0.99). Compared to non e-cig users, e-cig users had significantly higher problematic alcohol use in both samples (b's = 0.09 to 0.14, p's < .05). Expectancies of combined e-cig and alcohol use were significantly related to problematic alcohol use (b's = − 0.92 to 0.26, p's < .05). In sum, e-cig use is related to alcohol use and expectancies of combined e-cig and alcohol use; consequently, reshaping of beliefs about needs or desires to co-use could be a prime point of intervention.