Individual differences in pro-environmentalism (connectedness to nature, pro-environmental attitudes, and pro-environmental behavior) have been attributed to various personality traits and, most recently, socially/ethically aversive (aka ‘dark’) traits in particular. However, the empirical picture linking such traits to pro-environmentalism is scattered and has produced contradictory findings. We propose a more parsimonious and consistent explanation of individual differences in pro-environmentalism through the D factor, the common core of all aversive traits. Across 12 studies (total N = 13,882) we show substantial and consistent negative correlations (−0.56 ≤ r ≤ −0.26) between D and connectedness to nature, pro-environmental attitudes, and pro-environmental behavior. Moreover, the ‘dark tetrad’ traits (Machiavellianism, Narcissism, Psychopathy, and Sadism), alone or in their common combinations (as a triad or tetrad), never explained more total variance in either of these criteria than D alone. Finally, the extent to which any dark tetrad trait was negatively associated with pro-environmentalism was entirely due to D. These findings bear implications for the broader nature of pro-environmentalism and theoretical parsimony in research on individual differences in pro-environmentalism.