Foreign language programs in schools have a strong focus on the development of communicative language ability and, increasingly, assessment tasks are designed to capture communicative abilities required for real-world situations. In communicative test tasks, sociolinguistic and discourse components, which are beyond grammatical accuracy, target the abilities required to produce integrated texts that fulfil their communicative purposes. However, the majority of the work on assessment of communicative abilities has been carried out in the context of academic English, and less is known about the abilities of secondary students in foreign language teaching situations. This study examines the outcomes of an integrated writing task designed as part of formal year 12 assessment in Japanese as a second language. It seeks to elucidate the features which differentiate students at higher and lower levels of competence, and, through a focus on content and how it is presented, it demonstrates how these aspects of competence can be observed in responses to the task. The study contributes to our understanding of the nature of communicative abilities and their assessment in a secondary education context, and it also sheds light on aspects of competence which might benefit from more targeted teaching in such settings. Keywords: discourse competence, secondary school learners, Japanese as a foreign language, communicative writing task