In an increasingly connected world, a higher demand exists for global (citizenship) education in all disciplines, including mathematics. Although researchers in "Teaching Mathematics for Social Justice" (TMfSJ) have not ignored the need for a critical use of mathematics in society and culture, a primary goal of this work is to promote mathematics as a tool that can be used to analyze and act upon issues of social justice. Similarly, researchers in Global Education have developed frameworks over several decades identifying characteristics of individuals who can communicate effectively with others across cultural and language differences and act as responsible citizens of the world. While the goals of these fields align, additional research is needed to understand explicit theoretical connections between mathematics education and global education and provide examples of classroom tasks that effectively integrate mathematics content and issues of global (or national or local) significance. As a result, the primary goals of this study are to (1) identify instances of, and opportunities and challenges for addressing objectives of global education in the context of K-12 mathematics classrooms, (2) identify factors that influence the ways in which K-12 mathematics teachers design and implement mathematics tasks which integrate global issues, and (3) analyze selected mathematics tasks for the ways global education objectives are addressed and what factors influenced the design and implementation of a specific task. The participants of this study are all K-12 mathematics teachers and qualitative methods of data collection and data analysis are used in this study. [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.]