A meta-analysis investigated the effects of perceived injunctive (IN) and descriptive (DN) norms on behaviour (BEH) within the theory of planned behaviour (TPB) in a sample of 196 studies. Two related correlation matrices (pairwise and listwise) were synthesized from the data and used to model the TPB relations with path analyses. Convergent evidence indicated that the relation between DN and BEH was stronger than the relation between IN and BEH. Evidence also suggested a significant direct relation between DN and BEH in the context of TPB. A suppressor effect of IN on DN in its relation with BEH was also noted. Moderator analyses indicated that the DN–BEH relation was stronger when there was more time between measures of cognition and behaviour, when behaviours were not socially approved, more socially motive and more pleasant; results were mixed in the case of the IN–BEH relation. Results imply that IN and DN are conceptually different constructs.