The article considers Miyake's model of executive functions as applied to preschool age. The main objective of the study was to approbate the NEPSY diagnostic toolkit for assessing the level of executive functions development on a sample of Russian preschoolers (N = 267). As a result of comparing the results shown by US and Russian children aged 5-6 years, some specific cross-cultural features were identified: Russian children display a more developed image memory on average while their American peers showed a better memory for spatial representations. The speed of constraining control task performance averaged two times higher results in Russian preschoolers than in the Americans. To verify the convergent validity of the toolkit, a correlation analysis on a sample part (N = 48) was made of the results of the preschoolers' performance of two batteries of methods which was developed and tested under the guidance of L.A. Wenger. The revealed intercorrelation confirmed the possibility of using the above tools to diagnose executive functions. Analysis of the study data showed that the development levels of auditory and visual memory in older preschool children were not interrelated. However, in many respects verbal memory lies at the basis of attention flexibility development (switching), whereas visual memory underlies restraining control (inhibition). Based on the results of the diagnosis, four different variants of executive function development in the senior preschool age were identified and described.