This thesis is about informal learning of English as the first foreign language. It includes a small-scale study conducted with third and fourth grade primary school pupils (from 9 to 11 years of age). The study had a longitudinal design because it was conducted with the same participants (N=9) within a two-year period (when they were in Grades 3 and 4, in 2019 and 2020 respectively). The main aim was to determine informal sources of English the participants actively engage with in their free time through a vocabulary retrieval task. Additional aims were oriented towards comparisons of their engagements at different grade levels, as well as towards exploration of CEFR levels of informally acquired English. The findings of the study pointed at an increase in informal types of contact with English. However, no significant differences were found between sources reported in Grades 3 and 4 and in the amounts of English the participants were able to recall on their own. The findings are interpreted against results of similar studies in Croatia and elsewhere. Important implications of young learners’ exposure to digital sources of English language and to gaming activities for instructed settings are highlighted in the final section of the thesis. The study is believed to contribute to the understanding of language learning environment and its affordances in the process of English language learning in the Croatian context of early foreign language study.