Cannabis use among adolescents and young adults who drink alcohol is prevalent and relates to poorer clinical outcomes. Interrelated factors, such as cross-reactivity to alcohol cues, may contribute to the high prevalence of cannabis use among young persons who drink alcohol. We tested whether systematic presentation of alcohol cues in the laboratory and naturalistic presence of alcohol cues in daily life elicit cannabis craving. Data were compiled from two clinical trials. Participants (N = 54) were adolescents and young adults ages 15-24 who reported consuming alcohol at least twice per week, expressed interest in reducing alcohol use, and reported lifetime cannabis use. Participants provided laboratory and daily-life smartphone report data prior to randomization to treatment conditions in the parent trials. Mixed-effect models tested a priori hypotheses, which received mixed support. Cannabis craving was not heightened following alcohol-cue presentation in the laboratory but was elevated in daily life when alcohol cues were visible. The effect of laboratory alcohol cues was moderated by cannabis use frequency, with higher frequencies associated with greater cannabis craving, while the effect of daily-life alcohol cues on cannabis craving was not moderated by cannabis use frequency. Finally, alcohol cue-induced cannabis craving in the laboratory was associated with greater daily-life cannabis craving, irrespective of the presence of naturalistic alcohol cues. Overall, exposure to alcohol cues in daily life may flag situations with increased risk of cannabis craving, supporting the idea of cross cue reactivity and implicating naturalistic alcohol cues as an intervention target for individuals who co-use alcohol and cannabis. (PsycInfo Database Record (c) 2023 APA, all rights reserved).