This study tests whether age-related factors serve as effective predictors in one specific area of adult second language (L2), i.e. English word stress assignment by native speakers of Chinese. A perceptual stress preference task with English non-words of 2 to 3 syllables was carried out. Comparing the performance of English natives and Chinese EFL learners, it is found that age factors are good predictors of not only perceived global foreign accent but also the domain of L2 word stress placement. In addition, while both age of arrival (AOA) and length of residence (LOR) predict native-like stress placement of L2 learners, the model suggests that the predictive ability of AOA is stronger than LOR. It is therefore suggested that non-native-like stress placement is a substantial contributing factor to perceived foreign accent.