參照 Cummins 的語言相互依存假說（The Linguistic Interdependence Hypothesis）和閾限假說（The Thresholds Hypothesis），本文以香港一所標榜中英雙語教育的國際學校為案例，旨在探索港式中英雙語教育成效。通過運用（1）多元線性迴歸分析法（Multiple Regression Analysis）全面檢驗 251 位小學一至六年級學生中英雙語語文能力與超學科認知能力表現之相關性，評鑑 Cummins 的假說對解說港式中英雙語教育成效的適用程度；（2）ANOVA 變異數分析法（Analysis of Variance）探析 30 位小學一至六年級學生的中英雙語能力表現與其對中英雙語的態度及家長對中英雙語教育的態度之相關性，推論影響接受中英雙語教育學童語文能力不平衡發展的因素；（3）內容分析法（Content Analysis ）分析案例學校 10 位中英班主任和 3 位校長訪談內容、校本中英雙語課程大綱等，探討校本中英雙語教學模式與學生雙語能力發展的關係。研究發現：（1）Cummins的假說某程度能解說港式中英雙語教育成效，跨語實踐（Translanguaging）學理進一步完善和補充其假說；（2）在相同的校本中英雙語教育條件下，學生學習中英雙語的動機和對外語學習的焦慮程度、家長對孩子的期望值和對孩子學習的投入度、家庭社經地位、家庭用語偏向、不同持分者對雙語教育信念一致性、差異化教學的實施、社會語言生態環境等因素影響學童中英語文能力發展；（3）校本中英雙語教學模式有利於學生發展多重、整合的雙語實踐能力，具獨特的參考價值和發展意義。Based on Cummins's Linguistic Interdependence Hypothesis and Thresholds Hypothesis, this study aimed to examine the effectiveness of Chinese-English bilingual education in a bilingual international school in Hong Kong by using :（1） Multiple Regression Analysis to examine the correlation between Chinese and English bilingual proficiency and transdisciplinary cognitive ability of 251 primary Year 1 to Year 6 students, in order to evaluate the applicability of Cummins’s hypothesizes for explaining the effectiveness of Chinese-English bilingual education in Hong Kong; （2） Analysis of Variance to analyze the correlation between Chinese and English bilingual proficiency of 30 primary Year 1 to Year 6 students, their attitudes towards Chinese-English bilingualism and their parents' attitudes towards Chinese-English bilingual education, in order to infer the factors that affected the unbalanced development of Chinese and English proficiency of children who are receiving Chinese-English bilingual education; （3） Content Analysis to analyze the interview scripts of 10 bilingual class teachers and 3 principals, the school-based bilingual curriculum, etc. to explore the relationship between the school-based Chinese-English bilingual education model and the development of student's bilingual