The authors studied the prevalence of heavy drinking among students in 21 developed and developing countries using an anonymous survey of 7,846 male and 9,892 female students aged 17 to 30 years. There were wide variations in the prevalence of drinking among countries, and the highest rates of heavy drinking (defined as 5 or more drinks for men and 4 or more drinks for women on at least 1 occasion over the past 2 weeks) were reported in Belgium, Colombia, Ireland, and Poland (men), and Ireland and England (women). Heavy drinking was associated with living away from home, having a wealthier family background, and having well-educated parents. Beliefs about the dangers to health of excessive consumption were negatively related to heavy drinking. Heavy drinking is a concern among students in several countries and is associated with greater affluence. Challenging beliefs concerning health risks is a crucial aspect of prevention in this population. (Contains 3 tables and 1 figure.)