In second language acquisition studies, it has been observed that learners ' use of verb morphology is influenced by inherent lexical aspect. The purpose of this study is to go beyond inherent lexical aspect and in vestigate how the aspectual distinction between 'unitary and'repeated'situationtypes(Smith,1997)influenceslearners'andnativespeakers' useof verb morphology. The data ofthis study consist ofaudio-taped interviews ofeight subjects: three native English speakers, andfive learners whose native language is Mandarin Chinese. The results reveal that in relation to inherent lexical aspect, both learners and native speakers demonstrate similar skewed distributions of verb morphology in their speech. However, in relation to unitary vs. repeatedsituation types, learners and native speakers demonstrate different patterns in their use of progressive morphology: Native speakers tend to use progressive morphologyfor describing repeated situations, while learners use it to describe the ongoing, continuous nature of unitary situations. The findings suggest that learners' acquisitionalpatternsmaynotbedeterminedexclusivelybynativeinput. Theprototype account proposed by Shirai & Andersen (1995) provides a feasible explanation for the findings of this study.