Factors affecting the efficiency of second language learning

Abstract In a recent issue of System (System 9:1–3) Walter Apelt listed 10 leading principles in foreign language teaching, concentrating on fundamental issues and urgent problems. The purpose of this paper is to add a complementary list, of factors that affect the efficiency of second language learning. Many different studies have investigated different individual factors, but without providing a general overview or resume of all the different factors and how they relate to each other.