本文旨在探討第二語言環境的語言遷移現象。根據研究顯示，從第一語言到第二語言的正向遷移，出現於第二語言習得的初期，然此現象隨著第二語言程度的提昇而減少。此外，亦有証據顯示，從第二語言到第一語言的逆向遷移，可能發生於第一語言使用有限的環境，或是在第一語言語法之正確性無法得到確認的情況。本文探討臺灣籍與西班牙籍的美國大學研究生，按三種不同等級的英文程度，測試其第一語言與第二語言寫作，所有參與者都進行句法與篇章測試。結果顯示，台灣留學生的英文篇章出現正向遷移現象，而他們的中文句法出現逆向遷移現象。另外，中級台灣留學生的英文句法，其正向遷移與第二語言程度之關係呈U 型曲線。同樣地，中級台灣留學生的中文句法，逆向遷移與第二語言程度之關係亦呈U型曲線。本研究指出語言遷移的複雜現象，以及其與第二語言程度和不同測試任務之間的互動。

This paper focuses on the issue of language transfer in an L2 environment.
Research has shown that forward transfer from L1 to L2 appears at early stages and decreases as L2 proficiency increases. Additionally, there is evidence to suggest that backward transfer from L2 to L1 may occur in an L2 environment in which subsequent contact to L2 is limited or in an L2 academic community in which confirming evidence that L1 syntax is correct is lacking. The study of this paper investigates Chinese and Spanish learners across three English proficiency levels, who wrote in L1 and L2 at U.S. graduate schools. All participants completed sentence and discourse tasks. It is found that forward transfer occurred in the Chinese learners’ L2 writing at the discourse level and that backward transfer occurred in their L1 writing at the sentence level. Moreover, both forward transfer and backward transfer are mitigated by L2 proficiency. Furthermore, among the Level 2 Chinese learners, the relationship between forward transfer and L2 proficiency in the English sentence task follows a U-shaped curve, and the relationship between backward transfer and L2 proficiency in the Chinese sentence task also follows a U-shaped curve. The results of this study point to the complexity of language transfer and its interactions with L2 proficiency and distinctive task types.