Some recent data suggests that rises in obesity rates may be slowing or even plateauing, but this is not the case across the whole of society. More disadvantaged socioeconomic groups continue to experience disproportionately high levels of obesity. This presentation will provide an overview of evidence that speaks to why this might be the case. This evidence suggests that the key behavioural determinants of obesity – dietary, physical activity and sedentary behaviours – are also socioeconomically patterned, although not in the same way for all. We are continuing to discover why it is that obesity-related behaviours are themselves socioeconomically determined, with both individual-level and environmental and structural explanations emerging. There are also several alternative potential pathways linking socioeconomic disadvantage to obesity, such as via psychosocial stress. Collectively this evidence provides insights into potential intervention levers for initiatives addressing socioeconomic inequalities in obesity.