This study is concerned with the concepts of learner motivation, autonomy and identity in adolescent language learning. It investigates whether the use of intervention strategies influences adolescent learners’ autonomy and motivation in a language classroom setting. The intervention strategies in question are delegation of material and task selection to the student and promotion of self-evaluation. This study also reflects on the relationship between autonomy and motivation and the notion of identity/self in language learning. Thirty-two students and one teacher participated in this study, selected from an all girls’ secondary school in Ireland. The students were learning Spanish as foreign language. A quasi-experiment was designed which involved a treatment (18 students) and comparison (14 students) group. The teacher used intervention strategies to teach the treatment group, while continuing to use her traditional approach with the comparison group. This study predominantly used quantitative research methods, while qualitative research methods were used to collect data of a complementary nature. Quantitative data was collected via motivation and autonomy questionnaires, while qualitative data was elicited using goal-setting records, reflection records, individual interviews and classroom observations. The results indicate that motivation and autonomy levels increased significantly among the learners who were exposed to the treatment for the duration of the experiment, thus suggesting that intervention strategies are effective as regards generating motivation and fostering autonomy. The findings suggest that engaging in autonomous learning practices allowed students to use the language as a vehicle to express self and identity. The findings also indicate that adolescent language learners should be given a greater input in the learning process and would benefit from the inclusion of these or similar intervention strategies in formal classroom settings.