This document discusses the debate around using students' first language (L1) in the second language (L2) classroom. It outlines the history of approaches to L1 use over time, from bilingual methods to monolingual ones. While the dominant approach remains monolingual, the document discusses reasons both for and against strategic use of L1. It presents findings on the varying amounts of L1 used in classrooms and considers principles for its appropriate functions. The document raises questions about optimal L1 use and aims to stimulate discussion on balancing L1 and L2 in the multilingual classroom.