This cross-sectional study investigated the use of the simple past tense form by twenty Thai learners of English at two levels of proficiency. A cloze test developed by Ayoun and Salaberry (2008) was adopted. The findings showed that the learners in the high proficiency group used the past tense form more accurately than the learners in the low proficiency group. When verbs were categorized according to lexical aspect, both groups of learners were found to use the simple past tense form most often with telic events as well as with states. This did not correspond to the prediction of the Aspect Hypothesis, which asserts that low-level learners tend to the use simple past tense form with telic events first. The distributional bias in the input could account for the pattern found in this study.