Katikireddi SV, et al. – This paper explored the socioeconomic inequalities in developing multimorbidity, across the lifecourse. Furthermore, it assessed the contribution of five behaviour–related risk factors (smoking, alcohol consumption, diet, body mass index (BMI). It was illustrated that preventive measures focusing on known risk factors, especially obesity and smoking, could reduce the future multimorbidity burden. Major socioeconomic inequalities existed despite considering the known risk factors. Dealing with the social determinants of health, including holistic health and social care, was required if the rising burden of multimorbidity in disadvantaged populations had to be redressed.