The idea of a close relation between the work of the original Kostroma artist Efim Chestnyakov (1874-1961) and the traditional peasant culture has been expressed repeatedly. However, there were no direct parallels between the images and plots of his works and the folk rituals of the calendar cycle characteristic of the Kostroma land. In this regard, the purpose of this study is an attempt at a source analysis of the famous paintings by Efim Chestnyakov Our Festival and Festive Procession with a Song. Kolyada and verification of the previously stated hypotheses. For the first time, ceremonial rounds of courtyards on Yuletide and Saint George’s Day, as well as the carols (koliadki) and folk poems (prigovory) performed by their participants, are considered as the authentic basis of the fairy tales, paintings and clay figurines by Chestnyakov and at the same time as the context of the existence of his works when working with local children. Special attention in the article is paid to mummery as a game technique most in demand by Chestnyakov. According to his countrymen, the artist used disguises and masks traditional for mummery both inside folklore rituals, in which he involved his pupils — peasant children, and in theatrical productions based on folklore subjects invented for them.