Background: Since the 1930s, researchers have studied alcohol’s effects on emotions, behavior, and cognition in laboratory settings to understand factors that may contribute to alcohol use disorders (AUD). While most real-world drinking occurs in social settings—whether with friends, family, or strangers—laboratory studies seem to be overwhelmingly focused on solitary drinking. This discrepancy raises concerns about the ecological validity of laboratory alcohol administration studies and may limit our understanding of alcohol’s effects in naturalistic social environments. Here, we aimed to quantify how much laboratory alcohol administration studies have incorporated social drinking contexts. Methods: A systematic review was conducted of laboratory alcohol administration studies published through 2023, adhering to PRISMA guidelines. Searched in PsycINFO, PubMed, and Web of Science identified 5,690 records, from which 989 studies were included. Studies were coded for whether drinking occurred in solitary or social settings (see pre-registration for additional details https://osf.io/njvzd). Results: Of 989 studies identified, 90.8% administered alcohol in solitary settings, with less than 10% featuring a social context. Most multi-participant studies were conducted prior to 1990 and were methodologically limited by small sample sizes and inadequate statistical methods to account for interdependent participant interactions. More recent, well-powered multi-participant alcohol administration studies demonstrate alcohol’s robust effects on social bonding and tension reduction, mechanisms critical to understanding AUD risk. Conclusion: Current laboratory research largely overlooks the social nature of drinking, creating a gap in understanding alcohol’s typical effects and AUD risk factors. Well-designed multi-participant alcohol administration studies are urgently needed to address this gap, as they offer the potential to uncover social mechanisms underlying alcohol use and its associated harms. Prioritizing such research will improve ecological validity and may inform public health strategies for mitigating alcohol-related risks.