Predrinking (preloading, pregaming) has been found to be related to alcohol use and intoxication. However, most research relies on estimates of blood alcohol concentration and does not control for usual drinking pattern. We assessed whether predrinking was associated with subsequent alcohol consumption and breath alcohol concentration (BrAC) among 287 young adult bargoers (173 men [60.3%], Mage = 21.86 years, SD = 2.55 years) who were recruited in groups in an entertainment district of a midsized city in Ontario, Canada. We also examined whether predrinking by other group members interacted with individual predrinking in relation to amount consumed/BrAC. Adjusting for nesting of individuals within groups in hierarchical linear models, predrinkers were found to consume more drinks in the bar district and over the entire night compared to nonpredrinkers and had higher BrACs at the end of the night controlling for drinking pattern. A group- by individual-level interaction revealed that individual predrinking predicted higher BrACs for members of groups in which at least half of the group had been predrinking but not for members of groups in which less than half had been predrinking. This study confirms a direct link of predrinking with greater alcohol consumption and higher intoxication levels. Group- by individual-level effects suggest that group dynamics may have an important impact on individual drinking. Given that predrinking is associated with heavier consumption rather than reduced consumption at the bar, initiatives to address predrinking should include more effective policies to prevent intoxicated people from entering bars and being served once admitted.