The aim of this study is to evaluate learning and acquisition strategies used by second/foreign language learners. This study is a comparative investigation of learning and acquisition strategies of successful and less successful language learners. The main question of the study is to investigate if there is a relationship between the learners' strategies and their success; why some learners become less successful in language learning while others become more successful. Although there are many different answers to this question, in the study "the strategy" that the learners used has been scrutinized. The study, assessed the language learning strategies used by 92 university students in Turkey, using Oxford's (1990) Strategy Inventory for Language Learning (SILL). Also, one hundred and twenty university students in Turkey participated in an interview. They were grouped in into two parts as "successful" and "less successful" learners. The learners' levels were based on their scores in a standardized test administered at the beginning of their schools. In the questionnaire, T-Tests in statistical package for social sciences (SPSS) were used. In the interview, Fisher's Exact Test for 2x2 Tables and Chi-squared Test of Association Tests in SPSS were used. Both of the results reveal that there is a big gap between the students who use learning strategies and the ones who use acquisition strategies. The findings show that the language learners have different language learning strategies and these strategies can be grouped in two main title as learning and acquisition strategies. These findings have important implications for teachers, instructors and program designers to develop and practice different language strategies in order to have more successful students. At the end of the study, some suggestions were submitted to foreign language teachers and learners.