家庭母語流失轉向使用華語，是台灣族群語言保存siōng大ê威脅。台語雖bóng是台灣多數人ê母語，soah mā有流失到華語ê 現象。Chiâ^n chē家長kiohsī母語kap華語無法tō兼顧，kan-ta^n會當kéng一項。強勢ê華語chiâ^n做語言戰爭ê 戰勝者，弱勢母語直直敗退，流失chiâ^n緊。家庭是母語保存ê關鍵，mā是語言政策ê重要領域。家庭語言政策kap囡仔ê母語傳承有chiok要緊ê關係，mā是觀察母語保存成效ê指標。本文運用Spolsky（2004）ê語言政策架構，探討家庭成員ê語言意識形態、語言管理hām語言實踐。本文採用達成添加式雙語現象ê台語系台灣人（以下簡稱台灣人）家庭做對象，運用家庭語言政策ê理論，透過單一個案研究方法，探討某台灣人家庭按怎用「一人一語」ê方式，打造台語kap華語雙贏ê家庭。研究結果顯示，tī進行家庭語言政策規劃chìn前，家長需要有夠額ê母語意識形態，對雙語有積極正面ê看法，一人一語ê 分配著決定tī ang-á-bó語言能力kap使用慣勢，家長tī家庭透過語言管理，形塑雙語學習kap使用ê環境，hō囡仔發展出添加式ê雙語現象。家庭母語ê世代傳承是母語保存ê 基礎，本文呼籲家長愛kā傳承母語ê責任擔－起－來，積極規劃，實踐添加式ê家庭語言政策。

The shift of the mother tongue to Mandarin Chinese is the most serious threat to the preservation of Taiwanese languages. Even though Tai-gi Taiwanese (Taiwanese) is the mother tongue of the majority of the Taiwanese, it is also showing signs of shifting to Mandarin Chinese. Many parents are confused by the dilemma of choosing either Mandarin Chinese or their mother tongue. As Mandarin is the high variety, it has always been the winner in the language war, whereas the mother tongue has been defeated again and again. Family usage is the key to the maintenance of mother tongue, and it is also an important domain of language policy. Hence, the family language policy plays an important role in children’s acquisition of the mother tongues and functions as a framework to evaluate the vitality of the mother tongue. The paper uses Spolsky's (2004) language policy theory to explore family members' language ideololgy, language management and language practice. This paper is a single case study of a Taiwanese family, using their famiy language policy theory to find out how the family manage to achieve additive bilingualism through the One-Person-One- Language (OPOL) principle. The results show that parents need to have a strong mother tongue language ideology and positive attitudes toward bilingualism, before they start the language management process; and the arrangement of OPOL depends on the parents' mother tongue ability, strength of language loyalty and habitual language use. The paper shows that OPOL can be used to develop a family's additive bilingualism. It concludes with a suggestion for parents to get actively involved in the family's language policy.