Academic writing is a key skill through which students demonstrate knowledge of their subject areas and is most often the basis for assessing students’ work (Uysal, 2010). Unfortunately, international second language (L2) students often find academic writing challenging and confusing. Students need to be able to deal with these challenges by drawing on their resources, that is by demonstrating self-efficacy. The current research aimed to explore how self-efficacy impacted on L2 students’ perception of, and approach to, their academic writing practices, in their first year of study in New Zealand (NZ) universities. The study employed a longitudinal case study as its research methodology. Four study participants were interviewed regularly during the academic year. They also provided the researcher with their assignment instructions, marking criteria, and later, with the graded assignment and lecturer feedback. Findings indicate that the L2 learners’ self-efficacy fluctuated throughout their first year of study, which, in turn, was reflected in the ways the participants approached and responded to the challenges of their written assessments at different stages of their studies.