Brief interventions directed against hazardous and harmful drinking have become popular in recent years, both among researchers and, to some extent, among general practitioners and other health professionals. There is a strong evidence-base, at least in primary health care, to justify this popularity. But there is often confusion about what exactly alcohol brief intervention consists of. In fact, the term ‘brief intervention’ does not describe a single, well-defined activity but rather a family of interventions that differ in a range of ways. Although they all share the characteristics of being briefer than most formal treatment programmes for alcohol problems and of being aimed at drinkers with less severe problems and levels of dependence than those typically attending specialized treatment services, brief interventions differ among themselves in duration over time, number of scheduled sessions, procedures and accompanying materials, styles of interaction, delivery personnel and settings, and the underlying theoretical approach on which they are based.