Experts’ resistance to cognitive rigidity is discussed with reference to two aspects of the phenomenon of mental inflexibility: inter-domain rigidity and intra-domain rigidity. Although there are reasons to expect increased rigidity of experts outside the domain of their expertise, we hypothesized that they would be less prone to mental set within their domain of specialization. In two experiments (N = 72, N = 82), Experts, Intermediates and Novices solved tasks fostering mental set. Their goal was to solve a series of tasks of the same kind and then work on a task that was similar to the previous ones at the superficial level, while being substantially changed at the deep level of analysis. As a result, the effect of mental set (Einstellung) was expected to appear. The experiments were conducted in two different domains: management (Experiment 1) and English grammar (Experiment 2). Experts proved more resistant to intra-domain rigidity in both domains. In addition, they were faster and more accurate, thus replicating classic effects of expertise. The results regarding the role of anxiety in resistance to rigidity were unclear. The results suggest that, with reference to rigidity of experts, it is justifiable to distinguish between inter-domain and intra-domain rigidity. Experts, as compared to non-experts, should be regarded as more resistant to the phenomenon of intra-domain rigidity.