This is a review of the literature that supports content-based language learning. The articles and books reviewed cover recent literature as well as a number of key contributions that date as far back as the late 1980s. There are many commonalities between the earlier works and those of more recent origins since the authors grapple with similar concepts. These early inquiries into content-based language learning offer insights and discuss educational benefits in the areas of learning strategies, thematic teaching, sheltered instruction, collaborative learning, use of comprehensible input and concept development. The foundational literature is preoccupied with identifying areas of interest, while the more contemporary resources approach these issues more pragmatically. More recent texts read as "how-to" manuals for the classroom teacher. A number of additional themes emerge within this body of literature. Common instructional strategies are repeatedly cited as sound practice for the content-based language learning classroom. The development and use of native language is seen as advantageous to both learner and teacher. The learner builds cognitive resources and gains cultural knowledge, while the teacher is able to activate prior learning and build background knowledge. Under the umbrella of comprehensible input, the use of appropriate materials and visuals, modified language and scaffolding are discussed. While commonalities do emerge, the field is divided regarding direct instruction. There are two distinct camps, where one calls for direct instruction in all aspects of language, e.g., vocabulary, structure and concepts, and the other posits that learners will acquire the language when actively engaged in learning the content. While the line between the two approaches has been drawn, both sides do agree that vocabulary development is key to content-based language learning and collaborative active learning is essential in building language and content knowledge.