This document introduces the relationship between second language acquisition theory, applied linguistics research, and the insights of experienced language teachers as they relate to language teaching methodology. It argues that all three approaches should inform each other, but that in reality there is little interaction between them. The document outlines the three approaches: 1) second language acquisition theory, which consists of testable hypotheses about language learning; 2) applied linguistics research, which aims to solve practical problems through experimentation; and 3) insights from experienced teachers, which are based on observation rather than empirical research. It proposes that an ideal relationship would have information flowing between all three to mutually influence language teaching practice, but that currently there is little integration between theory, research, and practice