We explored the relationship between the fulfillment of students' psychological needs of competence, autonomy, and relatedness; student engagement; and student outcomes related to environmental literacy at a residential environmental education (EE) center. We surveyed diverse groups of middle school students (N = 1,278) following the completion of 80 EE lessons delivered at the NorthBay Adventure Center to assess their self-reported levels of these basic psychological needs, engagement, and environmental literacy outcomes. A structural equation model supported our hypothesis that there is a positive relationship between the fulfillment of these psychological needs and student engagement, and that more engaged students report enhanced outcomes of environmental literacy. We also discovered that autonomy has a direct positive effect on student levels of environmental literacy, suggesting an important role for student autonomy. We discuss implications of these findings and the practicality of trying to fulfill student's psychological needs of competence, autonomy, and relatedness.