It has been proposed that teenage girls often smoke cigarettes to protect themselves from the impulse to binge eat, with its feared weight-gain consequences, particularly when other measures such as greater dietary restraint have failed. The present study looked at the relationship between body mass index and standardised questionnaire responses concerning smoking, alcohol consumption, moods, weight changes, attitudes to body weight and shape, dietary patterns and menstruation in 1936 British (London) and 832 Canadian (Ottawa) schoolgirls. Data analysis revealed links between cigarette smoking and body weight/shape concerns, and awareness by subjects of these links; there was also a tendency for smokers in these two populations to be overweight but not grossly obese. Smoking was also related at all ages to being postmenarchal. The London population in particular revealed an association between smoking and a weight loss of 7 kg or more at some stage since puberty. Smoking was also linked, in a minority, with regular vomiting undertaken as a further defence against weight gain when overeating had occurred. These associations existed alongside the major and predictable association found between alcohol consumption and smoking. Similarities between the British and Canadian schoolgirls were striking in respect of rank order of reasons given for smoking and consequences of giving it up. Since smoking amongst older women is reportedly associated with below-average body weight it may indeed be effective in helping to curb weight gain. Our study provided little evidence of association between smoking and generalised anxiety or social anxiety (in either population), or depression (in the British cohort). We suggest that any preventive psychological approach to teenage female smoking should include attention to weight gain anxiety and consequent pursuit of thinness.