Abstract: To demonstrate professional multidimensionality ability to combine some directions, approaches and/or to carry out at the same time different kinds of activity the expert has to possess the special competences of integrative character such as multifunctionality and multitasking, a synergy and virtual mobility, therefore, they were called multidimensional competences. The experts possessing multifunctionality and multi-tasking gradually became multidimensional. Experimental studies showed, it didn’t matter in what sphere multidimensional experts worked, they achieved higher efficiency in research. The smaller part of experts reaches multifunctionality and multitasking easily, the most part does it long enough. On the basis of judgment of this fact, we formulated a research problem: what is psychological bases of professional multidimensionality formation. In the course of multifunctionality formation respondents had big difficulties in memorizing the information necessary for high-quality performance of new functional duties and during the multitasking formation difficulties in distribution of attention to some objects. So dependence of professional multidimensionality on such cognitive qualities of the personality as memory, attention and the related to it thinking was ascertained. During the experiment, we revealed that formation of professional multidimensionality takes place more successfully when memory is structured, attention is multivector and thinking is integrative and flexible. Research of dependence of professional multidimensionality on cognitive qualities of the personality allowed us to formulate the following conclusion: the psychological basis of professional multidimensionality of the expert is made by set of such intellectual qualities and abilities as structuredness and systemacity, the associative structured memory, multivectorness of attention, an integrative and flexible thinking.