The influence of person-organization Bt on employees' task and contextual performance was investigated in this study. It was hypothesized that the fit between employees' desired organizational cultures and their actual organizational cultures would predict contextual performance (e.g., helping behaviors toward other employees or the organization). It was found that (1) perceptions of the organizational culture and (2) the discrepancy between employees' ideal organizational culture and their perceptions of the actual organizational culture were important in predicting both contextual performance and task performance. Implications of these findings for organizational research and human resource management practice are presented. (C) 1999 Academic Press.