In the Australian education context, there are typically two cohorts of language learners at the secondary school level, those who commence their study of the target language early in their primary schooling (early starters), and those who commence their study later, at the beginning of secondary school (late starters). The two groups may have undertaken their language study under quite different program conditions, in particular in relation to "time-on-task"i. There is little empirical evidence about the nature of student achievement in languages at the end of primary and in junior secondary and its relationship to time-on-task. This paper compares the achievements of a sample of early and late start students of Indonesian in Australia using score data gathered from common measures of achievement. In addition, a small sample of student written responses are analysed in order to highlight issues related to eliciting and describing student achievement that may not be evident from the quantitative data alone. The findings of the study reveal the nature of achievement by early and late starters of Indonesian in the SAALE study, as well as the complexity of investigating a single variable such as time-on-task in relation to student achievement. The paper concludes by recommending that assessment of student achievement in language learning take into consideration methodologies that may capture more holistically a constellation of variables that impact on students' language learning.