Knowing how to use sources effectively often poses considerable challenges for first year undergraduate students for whom English is a second language (L2). In this longitudinal case study we investigated the selection and self-reported use of source materials by thirteen first year L2 undergraduate students from a range of disciplines enrolled at a major Australian university. Our findings show that students at the beginning of their studies selected material from a wide range of sources but relied predominantly on Internet sources using Google as a search engine. The main criteria guiding students' selection of sources were authoritativeness, ease of understanding and relevance. By the end of the first year, not all students (notably those from Engineering, Science and Music) were able to report further on their use of sources, as they had not undertaken any independent research in the second half of the year. In contrast, students from Arts, who also tended to be more proficient L2 learners, continued to undertake research-based assignments and demonstrated an awareness of the role played by task type, argumentation and writer authority in their selection and use of sources. We conclude this paper by considering the implications of these findings for EAP pedagogy and future research. (Contains 3 tables.)