Secondly, significant differences were observed among different proficiency groups in long term retention. The source of difference lied in high and low students. The results are in line with some previous studies such as Rubin (1975) who discussed characteristics of good language learners. Similarly, Chamot and El-Dinary (1999), Khaldieh (2000), Rubin (1975), Takeuchi (2003), Vandergrift (2003), and Yang (2007) asserted that good language learners use wide ranges of strategies. Thus, all the above strategies used by high proficiency students in Iran can provide a basis to aid less proficient language learners.