The increasing workload and volume of the DPR as an institution and individual DPR members, to maximize expertise, technical and administrative support provide by expert group to improve performance. This research aims to improve the organizational commitment of expert staff at the DPR RI or known as main parliament in Indonesia by analyzing direct effect and indirect effect of transformational leadership, employee engagement, and work stress on organizational commitment. The method used is descriptive analysis for processing qualitative data and inferential analysis for processing quantitative data. The data obtained from filling out the questionnaire were processed using the Lisrel structural equation modeling (SEM) software analysis technique on 325 people who were sampled.The results obtained are: (1) the transformational leadership direct effect on organizational commitment is significant, (2) the employee engagement direct effect on organizational commitmen is significantt, (3) the work stress direct effect on organizational commitment is insignificant, (4) the transformational leadership direct effect on work stress is significant, (5) the employee engagement direct effect on work stress significant, (6) the indirect effect of transformational leadership on organizational commitment through work stress is insignificant, (7) the indirect effect of employee engagement on organizational commitment through work stress is insignificant, (8) the indirect effect of leadership transformational on organizational commitment through employee engagement is significant. The Final model structure that suggested to measure organizational commitment in expert DPR RI was increasing transformational leadership through employee engagement as mediation.Keywords: organizational commitment, transformational leadership, employee engagement, work stress