In contemporary society, prolonged sitting has been engineered into our lives across many settings, including transportation, the workplace, and the home. There is new evidence that too much sitting (also known as sedentary behavior – which involves very low energy expenditure, such as television viewing and desk-bound work) is adversely associated with health outcomes, including cardio-metabolic risk biomarkers, type 2 diabetes, some cancers and premature mortality. In addition to the decreased energy expenditure induced through sitting, sedentary time may also be harmful because of the prolonged absence of muscle contractile activity in the lower limbs. Importantly, these detrimental associations remain even after accounting for time spent in leisure time physical activity – which within adult populations is infrequent and very low volume. This presentation will provide an overview of recent evidence from epidemiological and experimental studies. This new evidence is beginning to make a strong case that too much sitting should now be considered as a stand-alone element within public health recommendations – particularly for reducing the risk of type 2 diabetes and cardiovascular disease.