This study examines the potential benefits of using the native language of learners in a principled way by reviewing research that represents the dominant view of using only the second or target language (L2) against a growing body of literature that argues for principled L1 use. The development of the direct and monolingual method and its key aspects are discussed, and bilingual methods and arguments for implementing the first language (L1) in a foreign language classroom are reviewed and evaluated. An attitudinal case study investigating learners' attitudes towards L1 use in the classroom showed that students prefer a mixture of L1 and L2, and that the principled use of the L1 has positive effects on the learner. / by Isabel Osswald. / Thesis (M.A.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.