In the article we present the results of our research on the spirituality of Slavic Neopagans in Poland. Spirituality is understood here according to the concept of mysticism described by R. W. Hood Jr. (1975). As the second main theoretical tool, we use the concept of religious maturity put forward by R. L. Dudley and R. J. Cruise (1990). A questionnaire survey, conducted online on a sample of Slavic Neopagans and Catholics, showed statistically significant differences between the groups in three out of the eight subscales of mysticism (Unifying Quality, Inner Subjective Quality and Religious Quality), while at the same time showing a lack of significant differences with respect to religious maturity. Further analysis by means of binary logistic regression made it possible to determine predictors of belonging to the group of Slavic Neopagans (75.8% of the cases). In the regression model, the separate treatment of mysticism and religious maturity turned out to be insignificant, whereas gender, age, and the interaction between religious maturity and mysticism significantly differentiated the investigated groups.