As integrated writing tasks are becoming more common in assessment in EAP settings, there is need for more research to explore how different cultural groups perceive integrated writing assessment. With this in mind, this study aims to extrapolate students' perceptions of L2 English for Academic Purposes (EAP) in terms of their use of sources in an integrated writing assessment task and development as academic writers. It is necessary to comprehend students' perceptions towards source-based writing assessment tasks in order to set realistic goals and formulate effective instructional design for EAP programs. One hundred and thirteen undergraduate students completed the source-based assessment task, which required them to read texts and compose an argumentative essay by integrating relevant support from the texts. After the task, students were given an online questionnaire on their writing process. Student responses were analyzed quantitatively using frequency analysis and chi-square tests on SPSS across different self-reported proficiency levels. Analysis revealed highly positive perceptions and a significant relationship between reported proficiency, using sources as a repository for generating ideas, and modelling grammar and vocabulary. The study has implications for instruction and testing.