Objective: To assess trends in daily smokers’ social norms and opinions of smoking between 2002 and 2015 in Canada, US, UK and Australia.

Method: Data were from Waves-1 (2002) to -9 (2013-2015) of the longitudinal International Tobacco Control Four Country Survey (Canada, US, UK, Australia), involving 23,831 adult daily smokers. Generalised estimating equation logistic regression models, adjusted for demographics and survey design effects, assessed associations of Wave and country with outcomes: (i) over half of five closest friends smoke, (ii) agreeing that people important to you believe you should not smoke, (iii) agreeing that society disapproves of smoking, and (iv) negative opinion of smoking.

Results: Between 2002 and 2015, adjusting for covariates, (i) over half of five closest friends smoke did not change (56% vs. 55%; Adjusted Odds Ratio [AOR]=0.95[95% Confidence Interval=0.85-1.07]), (ii) agreeing that people important to you believe you should not smoke generally decreased (89% vs. 82%; AOR=0.54[0.46-0.64]) despite an increase around 2006-2007, (iii) agreeing that society disapproves of smoking increased between 2002 and 2006-2007 (83% vs. 87%; AOR=1.38[1.24-1.54]) then decreased until 2013-2015 (78%; AOR=0.74[0.63-0.88]), and (iv) negative opinion of smoking decreased between 2002 and 2010-2011 (54% vs. 49%; AOR=0.83[0.75-0.91]) despite an increase around 2005-2006 and at the final Wave (2013-2015). Except friend smoking, Canada had the greatest, and UK the lowest, anti-smoking social norms and opinions.

Conclusions: Except friend smoking and opinion of smoking, daily smokers’ social norms became less anti-smoking between 2002 and 2015 despite increases around 2006-2007. Several potential explanations are discussed yet remain undetermined.

Implications: Increasingly comprehensive tobacco control policies alongside decreasing smoking prevalence in Canada, the US, the UK, and Australia have led to the assumption that smoking has become increasingly denormalised in these countries. Absent from the literature is any formal assessment of social norms towards smoking over time. Contrary to our hypotheses, this study found that the injunctive social norms of daily smokers became less anti-smoking between 2002 and 2015, despite increases around 2006-2007. There was no change over time in the proportion of daily smokers who report that over half of their five closest friends smoke.