This two-year research proposal applies behavioral science to the systematic study of fraternity party environments in order to identify specific factors related to excessive alcohol consumption and intoxication of partygoers. The target population is university students (n=4,800) attending fraternity-sponsored parties (n=48) at a large university. The primary dependent variable is blood alcohol concentration (BAC) obtained from partygoers from 12:00 a.m. to 1:00 a.m. -- a peak time for most fraternity parties. The overarching practical objective of the proposed research is to identify environmental factors that can be used to develop policies and cost-effective prevention strategies for reducing excessive alcohol consumption and its concomitant negative effects among university students at social gatherings. The specific aims of this research are to: a) identify environmental factors related to excessive alcohol consumption at fraternity parties, b) identify and propose policy-related intervention strategies to address these environmental factors on a large scale, and c) explore ways to improve compliance with those university policies and guidelines for party drinking that significantly reduce at-risk drinking and intoxication, as determined objectively by the proposed research. Thus, the proposed research will not only provide an epidemiological analysis of environment-behavior and person-behavior relations related to excessive alcohol consumption at fraternity parties, but will derive a list of specific and feasible recommendations universities can use to decrease alcohol consumption at campus parties and thereby improve the safety of their students.