The aim of this research was to compare the quality of life among University of the Third Age (U3A) students in Poland, where a novel method of educating seniors is being developed, with the quality of life among students at newly established U3As in Belarus and Ukraine, which have copied the Polish model. The research was also conducted to connect a range of socio-demographic variables with two explanatory ones: satisfaction with participation in U3A activities and the overall quality of life. A total of 515 U3A (N13) students from three Eastern European countries—Poland, Ukraine, and Belarus—took part in the research. The overall quality of life of U3A students was researched and expressed in the form of three components: stress level, sense of self-efficacy, and level of satisfaction with life. The following tools were used: PPS10 (Perceived Stress Scale), GSES (General Self-Efficacy Scale), and SWLS (Satisfaction with Life Scale). The research showed a statistically significant difference between the country of residence and the level of satisfaction with life, sense of self-efficacy, and the overall indicator of the quality of life. Polish seniors obtained higher results in all these areas when compared to their counterparts in Ukraine and Belarus. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.