This study investigates the determinants of union members' satisfaction with their unions. Two theories of member satisfaction are formulated. In the first, satisfaction is hypothesized to be a function of specific union performances. The second theory relates satisfaction to the relationship between unions and their members. Constitutional procedures, in addition to performance, are the predicted determinants of satisfaction. A set of variables measuring union performance in various areas thought to be important to union members is constructed to test the first theory. In the second theory, labor union constitutions are viewed as explicit contracts between unions and their members, and various constitutional provisions are quantified and used as a set of satisfaction determinants. Performance variables are found to be the primary determinants of satisfaction, explaining the majority of the measured variation in satisfaction. The constitutional variables cannot be ignored, however, because when they are combined with performance variables they do contribute significantly, in a statistical sense, to the explanatory power of the union satisfaction model. It appears that constitutional "contracts" which specify officer removal and officer election procedures do help to solve union members' agency problems and thus increase their satisfaction with their unions.Ph. D.