AbstractUsing a detection test and an essay writing task, this study investigates the effect of home background on Chinese heritage language (CHL) learning and attainment at the advanced level. By examining the participants' use of target morphological marker le and discourse features, the study shows that, compared with their non-HL counterparts, advanced college CHL learners used the morphological marker le more frequently and more appropriately, and older CHL arrivals performed better than younger arrivals. Results of the essay writing task show that, compared with their non-HL counterparts, the older CHL arrivals did significantly better, while the younger arrivals did marginally better. The data support previous findings that early exposure to a language has undeniable positive effect on subsequent learning and that immigrant HL learners' age of arrival is an important indicator of attainment of competence at the advanced level.