Polish Baby Boomers Report More Private-Sphere Environmentalism than Generation Z

(1) Background: Each generation’s approach to private-sphere environmentalism is shaped by distinct historical and socio-economic contexts, values, educational opportunities, and living conditions. The aim of this article is to identify differences on this issue among four generations (BB, X, Y, Z) of Poles. (2) Methods: An online survey was conducted on a quota sample of 1000 individuals, with each generation represented by 250 participants. The sample was balanced across generations in terms of gender, education, and place of residence. (3) Results: The top private-sphere environmental behavior was waste segregation (M = 5.1, SD = 1.23), followed by using reusable bags (M = 4.92, SD = 1.2) and reducing energy use (M = 4.57, SD = 1.2). The older the generation, the higher the score in the private-sphere environmentalism index (F = 33.3 (3, 996), p < 0.001). Significant predictors of the private-sphere environmental behaviors (PSE) index were age, gender, environmental concern, and perceived self-impact on the environment, and the final hierarchical regression model explained 38% of the variance in the PSE index. (4) Conclusions: These results underscores the need to account for generational contexts when developing behavior-change strategies and sustainability policies aligned with SDG 12.