The purpose of this case study was to explore the barriers, or constraints, to the integration of field-based environmental education (EE) programs in K-8 public elementary schools in Phoenix, Arizona. Research continues to show that field based EE programs improve student outcomes (Bartosh, Tudor, Ferguson, & Taylor, 2006; Cole, 2007; James and Williams, 2017). Despite the empirical evidence, there appear to be obstacles to integrating field based EE into school curriculum. This study used Hierarchical Leisure Constraints Theory (HLCT) to identify and understand these constraints. There were 22 focus group participants and 13 interviewees from ten different schools and five school districts within the Phoenix area. Looking at the constraints identified by all participants, funding and the availability of transportation play a major role barring the use of field based EE programming. However, when applying HLCT, both of these barriers are structural in nature. This means these are constraints beyond the control of the individual but are negotiable. According to HLCT, you must first understand intrapersonal and interpersonal constraints and the effect they have on overcoming barriers. This study found that perception and prior knowledge emerged as the root of most constraints. In other words, while structural constraints are named as the primary issue in integrating field based EE in public schools, this study concludes from the findings that human nature and human values influence whether teachers and administrators participate in field based programming with their students.