We used data from 11 577 children in the UK Millennium Cohort Study, collected at approximately 14 years of age (early teens), to assess characteristics associated with smoking, and generated regional estimates of numbers of smokers. 13.8% of UK early teens studied had ever smoked; 1.9% were current smokers. This corresponds to 2 28 136 and 39 653 (13–14 year olds) in the UK, respectively. Ever smoking risk increased if caregivers (26.0% vs 10.9%) or friends smoked (35.1% vs 4.0%), with a dose–response effect for friends’ smoking. Caregiver and peer-group smoking remain important drivers of child smoking uptake and thus important targets for intervention.