The investments made in an interfirm relationship have implications for the effectiveness of an agreement. In this study, we investigate whether these investments influence the level of passive opportunism observed in a relationship. Whereas transaction cost theory suggests that firms that make idiosyncratic investments are reluctant to engage in opportunism, reactance theory offers logic suggesting that such investments may increase the likelihood of opportunism. In addition, we investigate whether perceived justice influences the effect of investments on levels of passive opportunism. Data from 120 retail managers in the Norwegian consumer electronics industry support reactance theory predictions and indicate that interactional justice moderates the relationship between specific assets and passive opportunism. We conclude with a discussion of the implications for theory and research.