This paper explores how learner background shapes learner performance on discourse features in writing by analysing data produced as part of the Student Achievement in Asian Languages Education project (Scarino et al., 2011) by Year 10 (mid-secondary school) students learning Korean as a foreign or heritage language. Five participants were in their second year of learning Korean as a foreign language at an Australian high school, whereas four Korean-speaking participants were learning their mother tongue in Saturday community schools and had varied experience of learning Korean and English, the language of mainstream schooling in Australia. Participants' performance on two writing tasks--one independent and one integrated--is examined in terms of two assessment categories--"forms and structures" (i.e., morpho-syntax) and "discourse" (i.e., coherence and cohesion). Results reveal that participants' performance within each group varies according to task types and that the pattern of within-group variation also differs between the two groups. It appears that the two types of learners respond differently to different types of tasks and that their learning is different in nature. It is concluded that this difference needs to be taken into consideration in teaching and assessment in languages education at the secondary school level. (Contains 1 table, 2 figures and 7 endnotes.)