Given the growing importance of English as a lingua franca, this study examines which context (classroom instruction in the students' home country vs. studying abroad in an English-speaking country) better facilitates the acquisition of English by learners of different ages: children, adolescents and adults. Participants (N = 197) completed several tests before and after their respective programmes so that we could explore their development of English oral and written skills in terms of fluency, lexical and syntactic complexity and accuracy. Results show that the "study abroad" (SA) context is superior to the "at home" (AH) context, especially for the development of oral skills. Additionally, when learning context is not considered, older students surpass younger students. However, when both learning context and age are taken into account, results reveal that younger SA participants tend to do better than older SA participants regarding oral skills, whereas results are less clear concerning written skills. Three important implications can be drawn from the present study: (1) there should be more SA programmes targeting children and adolescents; (2) primary and secondary schools should offer students the possibility of studying abroad for a term or two; (3) given the significant economic and educational implications, SA programme organisers should take into account factors that impede or facilitate the learning of foreign languages in order to maximise the effects of these stays abroad.