This research examined antecedent and outcome models for all four factors of union commitment (loyalty to the union, responsibility to the union, willingness to work for the union and belief in unionism). A hypothesis that union commitment would act as an intervening variable between the antecedents and outcomes was also tested. Unionized employees (n= 481) from a large mid‐western communications company completed a survey. Antecedents of loyalty to the union included national and local union mission fulfilment, and chief steward and officer accessibility. Chief steward accessibility and sex were identified as antecedents of responsibility to the union. Belief in unionism was predicted by local union mission fulfilment. Both national and local union mission fulfilment were significant antecedents of willingness to work for the union. All of the outcomes in the study, both behavioural (attendance at union meetings, union activity and member voting behaviour) and attitudinal (cognitive consideration in voting, member support for political action), were related to at least one of the four factors. Support was also found for establishing union commitment as an intervening variable between the hypothesized antecedents and outcome