This study describes the development and implementation of the Elementary School Teachers’ ePCK (EST:ePCK) questionnaire to measure teachers’ awareness about generalized PCK in the context of environmental education (EE). We compared responses of teachers who completed a graduate degree program designed to improve teachers’ pedagogical content knowledge (PCK) for EE with those who did not attend the program. This allowed us to consider the potential impact of such a program on teachers’ ePCK. Additionally, we examined what factors could contribute to differences in teachers’ awareness about ePCK beyond their participation in a professional development program. Findings show that teacher education programs can have a positive influence on teachers’ awareness about their own ePCK. However, in order to transform teachers’ classroom practices, programs need to offer more instruction about how to actually implement EE topics using integrative approaches and in real classroom contexts. Findings also suggest the need for additional research focused on understanding the kinds of PCK teachers need to be able to integrate instruction across several content areas and makes clear the need for programs to make explicit to teachers when program goals seek to develop different kinds of PCK.