This study investigated the influence of various factors associated with smoking behaviour among a randomly-selected sample of 3,000 Dublin post-primary-school pupils aged between 13 and 17 years. Normative influences on smoking behaviour were found to increase up to the age of 15/16 years and to decline after that.

The researchers related this pattern to the rise and decline of peer influences during these years. Family influence, particularly that of parents, in the example they set and in terms of their approval, was found to be constant over the same period. The contribution of beliefs to the prediction of smoking was found to be affected by age,

doubling in importance during the years considered in this study. The results had important implications for the understanding of susceptibility to social influence during adolescence and for the design of effective smoking prevention programmes.