The researcher found few studies that explore decisions of social studies teachers as they plan what and how to teach their classes. Over a century, social studies educators have adapted and responded to political, social, and economic changes. From educating immigrants a century earlier to addressing contemporary cross-border issues, social studies educators inherit unique challenges in today's increasingly globalized world. In addition to these external forces, constraints are placed on teachers which prescribe what content must be included in an already crowded curriculum. This qualitative approach using a case study provides a better understanding of the influence a globally oriented program has on participants' teaching social studies by investigating how participation in UNA-USA Global Classrooms program influenced how social studies teachers teach social studies. The goal was to provide a rich, compelling account of experiences of high school social studies teachers so that others can understand the issues reflected in their experiences better. The primary method of gathering data was the hour-long interview, in a case study approach. Analysis resulted in six themes: (1) teachers' perceived influence of Global Classrooms on student interest and engagement, (2) content expertise and confidence, (3) challenges to teaching global perspectives stemming from students, (4) challenges to teaching global perspectives stemming from school environment (5) innovative pedagogy and learning activities, and (6) projects and advocacy dimensions evolved from Global Classrooms experiences. Participants' unique experiences underscore the importance of studying the influence of globally oriented curriculum programs on social studies instruction. Implications include (1) teacher preparation and inservice training needs to be responsive to the need to develop an emerging cadre of teachers who are becoming increasingly aware of the need to infuse global perspectives into the social studies curriculum, (2) it is important that school districts realign professional development programs to help teachers gain content knowledge and expertise on global issues, (3) participants in this study confirm that globally oriented programs such as the UNA-USA Global Classrooms Curriculum enable teachers to build pedagogical content expertise in teaching about global issues, and (4) as pedagogical knowledge improved, participants became more adept at reinventing the curriculum and infusing components to serve the courses they taught. [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.]