An area which has gained ground in the field of second language acquisition research for over three decades is the study of language learning strategies (LLS). Learning strategies refer to special actions taken by learners to make learning easier, faster, more self-directed, more effective and more transferable to new situations (Oxford, 1990, 2003, 2011). The favourable results of many intervention studies have provided a strong indication that the use of LLS is likely to lead to achievement in the foreign language and also contribute to learner autonomy.The purpose of this study is to investigate the outcome of providing Libyan adult learners of English with formal training in the use of LLS. This training took the form of strategies-based instruction (SBI) within a collaborative action research framework. The research examines the contribution that SBI might offer the learners in relation to the development of all four language skills (i.e. listening, speaking, reading, and writing) and the development of learner autonomy. The impact of SBI on teacher roles and professionalism was also part of the investigation.The investigation as a case study relied on 61 student participants from three different levels of proficiency: elementary, pre-intermediate and intermediate levels. To implement the SBI approach, all three classes followed the four phases of the Strategies-Based Instructional and Assessment Model which was specifically designed for the current investigation. The model, which adopted a multi-method approach to data collection, was implemented with the collaboration of three different class teachers.Findings of the study revealed that the SBI intervention helped raise both the teachers' and students' awareness of LLS. The programme increased students' overall strategy use and had an impact on their learning efforts and language skill improvement. The development of learner autonomy (closely associated with an increase in metacognitive and social awareness) was a major outcome of the study. Results also showed that the study had an impact on the three participant teachers in terms of professional development having implemented SBI for the first time and also as a result of their collaboration in action research. A construct of teacher beliefs was revealed and attitude change particularly towards learner autonomy was also noticed among the teachers
