This study aims to investigate the difference between perceptions among adolescents towards autonomy considering the European Language Portfolio Use (ELPU) and the effects of autonomy and ELPU on English attainment. It further scrutinizes how European Language Portfolios (ELF) and autonomy promoting strategies are used. The participants comprised 309 6th-8th year students in their early adolescence and 11 teachers in two private primary schools in Ankara and Adana. A 'sequential explanatory' research design was applied. Results revealed that the students who did not use ELP scored higher on the 'Adolescent Autonomy Scale' and 'Language Learning Autonomy Scale (LLAS)' than those who used ELPs. LLAS scores were the significant predictors of the English attainment. Furthermore, the ELPU was not supported with autonomy promoting strategies.