This study used structural equation modelling to examine the effects of sociodemographic variables and outdoor recreation participation on pro-environmental behaviour (PEB) among an ethnically diverse population of adult state-park visitors near Atlanta, Georgia, USA (N ¼ 319). Data collected through intercept surveys at three state parks were used to examine interactions among potential predictors of PEB, including socio-demographics (ethnicity, gender, education, and income), outdoor recreation participation (during childhood and adulthood), and environmental value orientations (biocentric and anthropocentric). The best fitting model accounted for 40% of the variance in self-reported PEB and indicated the strongest positive relationship between adult outdoor recreation participation and PEB (b ¼ 0.54, t ¼ 5.70). Biocentric and anthropocentric value orientation scores were also significant antecedents of PEB (b ¼ 0.17, t ¼ 1.99, and b ¼ 0.19, t ¼ 2.56, respectively), and both were influenced by socio-demographic variables. Overall, results suggest that a diverse public's environmental ethos and propensity to engage in PEBs could be influenced by outdoor recreation opportunities.