巴賽(Basay)是原來住在大臺北地區的平埔族。本文主旨在使用語言的資料和現象來探討巴賽的地位問題：(一)巴賽隸屬於臺灣還是西部南島語？(二)巴賽在臺灣南島語言中的地位，它跟哪些語言較接近？ 音韻演變的證據顯示巴賽也是一一種道地的臺灣南島語言，尤其是它何存了古南島語的*S為s，如*bukəS>bukəs’頭髮’。 巴賽語跟噶瑪蘭語的類緣關係最接近，包括詞彙、音韻、構詞、周法等各層次的證據。它們有五種共同的音變，其中兩種音變只見於比賽與噶瑪蘭，是屬於這兩種語言的共同創新。此外，還有幾個同源詞又共有很特殊的演變：*susu>巴cicu，噶sisu’乳’(元音異化)，*piliq>巴pam-ici，噶pam-ili’選’(鼻音取代語根首輔音paN-)，這些不常見的演變可說是兩種語言關係最密切的強有力證據。在構詞方面，人稱代詞有相關的形式與功能。在句法方面，受事焦點與處所焦點在這兩種語言都合併了。 此外，本文也初步探討巴賽－噶瑪蘭群跟西拉雅、阿美的親疏關係。

Basay, the plains tribe language formerly spoken in northern Taiwan, contains Formosan as well as extra-Formosan features. Its vocabulary includes baηka ‘canoe,’ puti ‘banana,’ manuk ‘bird’ and bilaη ‘to count’ that are found only in western Austronesian languages. It is argued that these lexical items were borrowed from Philippine languages during Spanish occupation of northern Taiwan. Crucial evidence comes from phonology, e. e., the retentioin of Proto-Austronesian *S as s in the basic vocabulary, such as * bukəS>bukəs ‘hair,’ *Səpat> səpat ‘four’ and *iSu>isu ‘you, sg.’ It is concluded that Basay is a Formosan rather than extra-Formosan language. Another aim of this paper is to determine the linguistic position of Basay among Formosan languages. Basay and Kavalan share the following sound changes: (1) merger of *t and *C, (2) merger of *D and *Z, (3) merger and loss of *q, *H and *? (4) merger of *j, *n and *N, and (5) split of *k into k and q, the latter of which further underwent the change q>h in Basay, but not in the closely related innovations in Basay and Kavalan. Shared innovations are also found in the sporadic changes in a few lexical forms, such as *susu>Bas cicu, Kav sisu ‘breasts’, *ku(S)kuS>Bas K< an >ukus, Kav q<n >uqus ‘finger nail’, and *piliq > Bas p-am-ici, Kav p-am-ili ‘to choose’. Bath languages have very similar pronominal systems, including the shift from genitive to nominative in all or most of the forms iku, isu, ita, imi and imu. Patient-focus and Locative-focus have merged in both Basay and Kavalan. In shrot, linguistic evidence for the close relation between Basay and Kavalan is found at all linguistic levels: lexicon, phonology, morphology and syntax. To which language(s) is the Basay-Kavalan subgroup most closely related? Blust (1999) posits an “East-Formosan” group, which includes the following three subgroups, BasayKamis and Siraya. There is conflicting linguistic evidence for grouping Siraya with Amis or Basay-Kavalan. Anthropological evidence, especially the social organization, indicates that Siraya is most closely related to Amis. Thus our tentative subgrouping hypothesis is that Basay-Kavalan and Siraya-Amis are the two main subgroups of this East-Formosan group. Further study is required to determine more precisely the internal relationships of these four Formosan languages.