The assumption of new challenges and services to provide, and the evolution of new technologies in public administration, give employees an important perception of ambiguity when carrying out their work. Role ambiguity has been conceptualized as one of the main impeding demands at work with negative consequences. The objective of the present study is to analyze the moderating effect of the support by the department head in the negative influence of the role ambiguity on the engagement and the extra-role performance behaviors of the employees. The hypothesis is proposed that the support of the department head will mean the transformation of role ambiguity into a challenging job demand with positive results. A total of 315 public employees with administrative staff have participated in this study. Results confirmed that the support of the leader moderates the effects of role ambiguity. The inclusion of this variable as a moderator transforms the influence of role ambiguity on the employees’ engagement into a positive one and reduces their negative effect on extra-role performance behaviors. These results reinforce the role of leader support as a protective element against job demands in public administrations. Theoretical and practical implications and future lines of research are discussed at the end of the work
