Appropriate preparation for preservice and inservice teachers for teaching content-area literacy continues to influence twenty-first century research agendas. In this systematic review (which analyzed 2,179 articles), the researcher aimed to ascertain and synthesize the research on teacher preparation for content-area literacy instruction while evaluating the methodological qualities of the research. The findings are presented in an article format with the connecting theme of content-area literacy; however, the first article focused on research regarding preservice teachers and the second article on inservice teachers. Whereas, previous reviews have primarily focused on secondary teacher beliefs and attitudes this review provides a broader scope of the research, which encompasses K-16 preservice and inservice teachers’ beliefs, attitudes, instructional practices, strategies, and knowledge of content-area literacy instruction. The major findings from research on preservice teachers are: with a minimum of one content-area literacy course, this teacher preparation may prove to be less than sufficient; in addition, preservice teachers’ beliefs regarding content-area literacy are typically positive, but actual transference once in the classroom is narrow. The major findings from the inservice article suggest the need for further training, modeling, and collaboration of literacy instruction for implementation in content classes. Inservice teachers, albeit experts of their content are restricted by their own motivation and knowledge of literacy strategies, therefore literacy implementation during class instruction is restricted. By reviewing longitudinal and current research as well as building upon previous reviews, these articles closely examine preservice and inservice teacher preparation, instruction, and implementation of literacy instruction in the content-area class.