本研究旨在調查國中智能障礙學生之自我決策能力現況及影響其能力高低之因素，另亦評估教師與家長對學生能力發展所提供之支持情形，及此支持與學生能力之相關及對能力之預測情形。研究以立意取樣方式從北部某縣11所國中選取不同障礙程度之智能障礙學生 (n＝100)、普通班非身心障礙學生 (n＝100)、特教教師 (n＝ 50) 及智能障礙學生家長 (n＝100) 共350名為研究對象。參與者按其身份填寫本研究自編之「國中學生自我決策量表」學生、教師或家長版以評估智能障礙學生在自我瞭解、心理賦權、自我調整及獨立自主等四個向度及整體的自我決策能力。使用的資料分析方法包括描述統計、相關分析、變異數分析及迴歸分析。研究結果顯示，國中智能障礙學生的自我決策程度不高，且顯著低於其非身心障礙同儕。智能障礙學生的自我決策程度主要受其性別、障礙程度、目前安置型態、國小安置型態、父母社經地位、家庭結構、居住型態及教養態度等因素影響。雖然教師背景變項並不影響學生的自我決策程度，但其與家長所提供的支持卻與學生能力呈高度相關。但令人失望的是，學生僅從此兩者獲得中間程度的支持。此外，教師及家長的支持能有效預測學生的能力。研究最後針對結果提出具體教學、教養及研究建議。

The major purposes of this study were to (a) investigate the level of self-determination competency of junior high school students with intellectual disabilities (ID), (b) identify factors that affect the development of student competency, (c) examine the level of support provided by teachers and parents, (d) analyze the correlation between the level of self-determination competency and level of support received, and (e) examine how well the level of support received in predicting self-determination competency. Subjects included students with ID (n＝ 100), students without disabilities (n＝100), special education teachers (n＝100), and parents (n＝50) of students with ID. Students were recruited from eleven public junior high schools. All participants were required to complete a self-determination scale including three versions designed for students, teachers and, parents respectively. Data collected were analyzed using descriptive statistics, Pearson correlations, analyses of variance, and regression. Findings showed that students with ID in junior high school demonstrated the medium level of self-determination competency and scored significantly lower than their peers without disabilities. The factors that affect the level of the self-determination competency of students with ID included student gender, severity of disability, current placement status, placement status in elementary school, socioeconomic status, family structure, family living style, and parental rearing philosophy. Although the background experiences and demographic factors associated with teachers did not affect the self-determination competency of students with ID, there was a highly positive correlation between the level of student competency and the level of support provided by teachers. However, students with ID merely received medium level of support from their teachers as well as parents. Additionally, teacher and parent support is a good predictor of students' self-determination competency. Suggestions were further provided for special education teachers, parents, as well as prospective researchers.