The autonomy of learners (AL) is a concept that is increasingly becoming popular in English Language Teaching (ELT). This study sought to explore the effects of in-service training on the perceptions and practices of Iranian EFL teachers in terms of learner autonomy. The use of mixed methods enabled the collection of both quantitative and qualitative data from the Learner Autonomy Questionnaire (LAQ) (Borg & Al-Busaidi, 2012) as well as classroom observations and semi-structured interviews. Twenty teachers from an Iranian EFL context enrolled in a 30-hour in-service training focusing on autonomy-supportive practices for EFL. The results of quantitative data analyzed through descriptive statistics and repeated-measures ANOVA showed significant differences on teachers’ perceptions (F = 93.57, p = .00, η2= .83) and practices (F = 237.52, p = .00, η2= .92). Thematic qualitative analysis of interviews showed that teachers’ beliefs with regard to learner autonomy became comprehensive and multi-faceted resulting in greater use of reflective practices, goal-setting, and collaborative problem solving. These findings corroborate existing literature, , while also emphasizing the need to incorporate practical training as a component in teacher development programs (TDP) in a bid to transform knowledge into practice within the classroom. These findings are relevant to curriculum development, teacher training, and future learner autonomy research in EFL contexts.
