Socioeconomic inequalities in adolescent health have been little studied until recently, partly due to the lack of appropriate and agreed upon measures for this age group. The difficulties of measuring adolescent socioeconomic status (SES) are both conceptual and methodological. Conceptually, it is unclear whether parental SES should be used as a proxy, and if so, which aspect of SES is most relevant. Methodologically, parental SES information is difficult to obtain from adolescents resulting in high levels of missing data. These issues led to the development of a new measure, the Family Affluence Scale (FAS), in the context of an international study on adolescent health, the Health Behaviour in School-Aged Children (HBSC) Study. The paper reviews the evolution of the measure over the past 10 years and its utility in examining and explaining health related inequalities at national and cross-national levels in over 30 countries in Europe and North America. We present an overview of HBSC papers published to date that examine FAS-related socioeconomic inequalities in health and health behaviour, using data from the HBSC study. Findings suggest consistent inequalities in self-reported health, psychosomatic symptoms, physical activity and aspects of eating habits at both the individual and country level. FAS has recently been adopted, and in some cases adapted, by other research and policy related studies and this work is also reviewed. Finally, ongoing FAS validation work is described together with ideas for future development of the measure.