The present study reports on a small-scale investigation of Mandarin aspectual marking among two groups of pre-intermediate learners of Mandarin Chinese: native English speakers and native Korean speakers. The use of -le, -guo, and -zhe in the learners’ written work was examined, with particular attention to three variables: (i) overall frequency of aspectual marking, (ii) frequency of occurrence of each marker, and (iii) interaction between these markers and situation types (Smith 1997). The learners’ patterns were also compared with those of a group of native Mandarin speakers and analysed in terms of the postulates of the Aspect Hypothesis (Andersen & Shirai 1996, Bardovi-Harlig 2000). The overall analysis discerned both similarities and differences in the usage of the three markers among the learners. Such patterns are likely to be related to the distinctive nature of the markers, type of genre, the learners’ L1 aspectual systems, and classroom/textbook input.