One of the main goals of Environmental Education (EE) is to develop people's environmental stewardship, which includes people's capacity to take environmental action--their action competence (AC). The purposes of my study were to characterize the interactions found in an EE curriculum, science teachers' pedagogical content knowledge (PCK), and their use of AC, and to identify factors that appear to be associated with the use of AC in curriculum and instruction. My study was divided into three parts: (1) content analysis of the Water Quality Unit of the Michigan Environmental Education Curriculum Support (MEECS, nine lessons); (2) a survey of MEECS training participants (N=131 [28.4% response rate]); and (3) an in-depth examination of pedagogical content strategies and use of AC of four science teachers using class observations (December 2007-April 2008: N=38), semi-structured interviews (October 2007-April 2008: N=20), Content Representations (CoRes: N=6), and surveys (N=4). The extent that individual elements of AC occurred in each data source was variable; that is, some elements were more prevalent in one data source than another. Of the five elements of AC, "knowledge/insight, planning and action experiences, and critical thinking and reflection" were more prevalent than "commitment" and "visions" in two of the three data sources, namely, the Water Quality Unit (EE curriculum) and the four teachers. "Visions" was consistently the least prevalent element of AC in each of the three data sources. In general, the types of and/or extent that goals and beliefs, pedagogical approaches, instructional methods, student skills foci, and manifestations of PCK occurred helped explain the prevalence of individual elements of AC across the data sources. For example, use of "activity-driven, project-based," and "process-oriented" pedagogical approaches appeared important for engaging students in real world "planning and action experiences". Other factors that appeared to be associated with the use of AC include content taught, personal conviction of teachers, barriers or constraints in teaching context, characteristics of students, and teacher education and professional development experiences. To strengthen use of AC in EE curricula and by teachers, some recommendations include: 1) changing standards and assessments to include the use, development and measurement of AC; 2) emphasizing equally all the elements of AC in curriculum development and instruction; and 3) training teachers on the use of multiple approaches and methods for applying AC in and outside of the classroom, as well as the importance of being intentional and reflective about one's teaching, to help build one's PCK for teaching EE and fostering students' AC. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]