This chapter begins by outlining the key ideas and problems of the theorizing of teaching as discussed in selected English-language literature published over the past six decades. The focus is on the value of theories of teaching and the ways theories of teaching and related terms have been defned. After creating a synthesis of the various attributes which researchers have suggested can be used for assessing the quality of theories of teaching, we discuss the process and diffculties of generating theories, and present a summary of theories of teaching found in the literature. The second part of this chapter clarifes the aims of this book, describes the sampling criteria for the selection of contributors, provides an overview of the structure of the book, and lists the questions that the contributors were asked to address.