Most cross-national studies of crime and violence explore variation in levels of crime without empirically addressing the causes of these variations. Drawing upon the theoretical framework of the situational action theory of crime causation (e.g. Wikström 2006), in this study we aim to explore and test whether the difference in levels of violence among young people in England and Sweden can be explained (fully or partly) by country differences in young people's crime propensities and lifestyles and their interaction. To achieve this we use data from the English Peterborough Youth Study and the Swedish Eskilstuna Youth Study. The findings show that in both cities (1) young people's self-reported violent behaviour is predicted by crime propensity and lifestyle, and their interaction, and (2) a substantial proportion (40 percent) of the difference in the level of violence vanishes when taking into account national differences in young people's crime propensity and lifestyles. We conclude that the findings support the notion that one major cause of the difference in the level of violence among young people in England and Sweden is that more young people in England have a higher crime propensity and are living criminogenic lifestyles than in Sweden.