Abstract:The goal of the present research was to examine how organizational support and organizational commitment influence the relationship between developmental performance appraisal and the employees' task performance. A number of 217 formal employees working at Gas Company in Gilan, Iran with a degree of diploma and beyond were selected to answer a questionnaire in a stratified random manner. The research method was a cross-sectional survey type (structural equation model). Research instruments adopted in this study included Questionnaire of Developmental Performance Appraisal (Kuvaas, 2007), perceived Organizational Support scale (Rhoades et al., 2001), Organizational Commitment Questionnaire (Balfour andWechsler, 1996), as well as Task Performance Questionnaire (Williams and Anderson, 1991). To evaluate the suggested model, structural equation modeling through PASW Statistics22 and Amos Graphics21 software package were used. Moreover, the indirect effects were tested by Bootstrap procedure. The results revealed that the research suggested model enjoyed a good fitting with data. The findings does not support direct path of developmental performance appraisal and task performance .The research findings showed that indirect path of developmental performance appraisal, organizational commitment and organizational citizenship behavior was meaningful, while the indirect path of developmental performance appraisal, organizational support and task performance were not supported. Eventually, Implications and directions for future research are discussed.