We report a study of intergroup relations in a paper factory in which we examine the utility of three social-psychological approaches: realistic conflict theory, the contact hypothesis and social identity theory. A sample of 177 shop floor workers from five different departments was interviewed. From them, measures of intergroup differentiation, perceived intergroup conflict, amount of intergroup contact, and strength of workgroup identification were obtained. The latter was assessed using a new scale of group identification developed for this study. Reliability and validity data for this scale are reported. Using multiple regression analyses we attempt to explain variance in respondents' intergroup differentiation using the other measures as predictor variables. The most powerful and reliable predictor was perceived conflict which, as expected, was positively correlated with differentiation. Less consistent was amount of contact which was negatively but only weakly associated with differentiation. Strength of group identification, while generally showing a positive correlation with differentiation as predicted, was also only a weak and inconsistent predictor variable. Noting that these results confirm findings from other studies we discuss their theoretical implications.