現今國中學生寫作動機與作文品質不佳是國內普遍的現象，而學校是國中學生的主要學習場所，因此本研究的探討旨趣在於瞭解校園中的三個主體：學生、同儕與教師，即文化資本、同儕互動以及內化判準，與國中學生寫作動機以及作文品質間的關係；並進一步瞭解國中生的文化資本、同儕互動、內化判準對寫作動機的預測情形以及前述四者對作文品質的預測情形。 本研究以163位國中二年級學生為研究對象，研究工具包括：研究者自編的「文化資本量表」、「同儕互動量表」、「內化判準量表」、「寫作動機量表」以及「作文評定量表」。此外，本研究以因素分析、信度分析、t考驗、單因子變異數分析、皮爾遜積差相關分析、典型相關分析以及多元迴歸分析進行量表與研究假設的驗證。 研究結果顯示： 1.當國中生擁有愈多的文化資本，其寫作動機也會愈高；而國中生擁有的文化資本多寡，與其作文品質無明顯的關係存在。 2.當國中生與同儕的互動頻率愈高時，會有愈高的寫作動機，且會有愈良好的作文品質。 3.當國中生對寫作判準的認同程度愈深時，會有愈高的寫作動機，且其作文品質會愈良好。 4.當國中生的寫作動機愈高時，其作文品質也會愈良好。此外，當國中生的寫作訊息性動機愈高時，其作文中也會有愈良好的新穎性表現；而國中生的寫作內在動機與控制性外在動機對作文中的新穎性表現沒有顯著的影響。 5.國中生已認同判準以及文化資本能顯著預測國中生的寫作動機，且國中生已認同判準是最主要的預測變項。 6.國中生已認同判準、訊息性外在動機以及同儕互動能顯著預測國中生的作文品質，且國中生已認同判準是最主要的預測變項。 為促成國中學生寫作動機以及作文品質之有效提升，本研究最後根據研究結果，對國民中學與國中教師提出幾點實務上之建議： 1.國中校園應多提供豐富的語文物理環境，並鼓勵學生多加運用；此外，鼓勵學生多參與多元的活動，累積生活經驗。 2.鼓勵國中同儕間建立分享的寫作學習社群，並積極地和同儕討論生活見聞。 3.協助學生掌握寫作領域中的批判性原則與標準。 4.著重國中生之寫作訊息性外在動機以及內在動機的培養。 並從研究議題與研究設計兩方面提出建議，作為後續研究之參考。 關鍵字：文化資本、同儕互動、內化判準、寫作動機、作文品質 / Low writing motivation and inferior composition quality has been a general phenomenon for current junior high students. In view of school as the main learning field, this research is to investigate how writing motivation and composition quality are related with cultural capital, peer interaction as well as writer’s internalized criteria, how the writing motivation is predicted by cultural capital, peer interaction as well as writer’s internalized criteria, and how the composition quality is predicted by cultural capital, peer interaction, writer’s internalized criteria and writing motivation. There are 163 students of grade 8 joining in this research. Five self-reported questionnaires, which are “cultural capital scale”,“peer interaction scale”,“writer's internalized criteria scale”, “writing motivation scale” and “composition quality scale” , designed by the researcher, were utilized to measure each variable respectively. Factor analysis, Cronbach alpha, t-test, ANOVA, Pearson relation coefficient, canonical correlation analysis and multiple regression were conducted to validate the questionnaires and verify the hypotheses. The results were as follows: 1. The more cultural capital, the higher the writing motivation were. However, cultural capital was not related with composition quality. 2. The junior high students, who interacted with classmates more frequently, have higher writing motivation and better composition quality. 3. The more important students identified the writing criteria, the better composition quality were. 4. When students owned higher writing motivation, their compositions also have better quality. Besides, when students have higher informational extrinsic motivation, their compositions were found more novel. However, neither of the intrinsic writing motivation nor controlling extrinsic motivation impacted the novel performance. 5. Both identified writing criteria and cultural capital were able to predict writing motivation significantly, the former variable is the most important one. 6. Composition quality was able to be explained by identified writing criteria, information extrinsic motivation and peer interaction significantly. Identified writing criteria is the most important variable among them. Based on our results, several suggestions were raised for the practical application of teachers. 1. The campus should be generated as an abundant linguistic surroundings and the school should encourage students to utilize those resources more frequently. Besides, school should inspired students to participate the various activities so as to enrich the living experiences. 2. The writing community should be encouraged to establish for sake of share of learning experience. The discussion regarding living experiences among classmates should also be promoted. 3. To help the students mater the critical principles and standard in writing field. 4. To generate both intrinsic and informational extrinsic motivation for junior high students. Keywords: cultural capital, peer interaction, writer's internalized criteria, writing motivation, composition quality