The present study aimed to examine the mediation effect of students’ motivation in the relation between students’ self-concept and achievement, considering the different regulation types described by Self-Determination Theory. The central objective of our study was to determine if autonomous and controlled motivation types in different school-subjects would mediate differently the relation between self-concepts and achievement. Indeed, autonomous motivation types have been shown to be more related to academic outcomes than controlled ones, and therefore we expected that this would result in differential mediation effects. A 2-wave study was carried out on a sample of 411 high school students in grades 9 and 10. Students’ self-concept, self-determined motivations and grades were assessed in 4 different school-subjects (i.e., math, French, English, physical education). Results confirmed our hypothesis and showed that autonomous motivation types mediated the contribution of self-concept to achievement in corresponding school subjects whereas controlled motivation types did not. Educational and methodological implications are discussed and location of introjected approach regulation on the relative autonomy continuum is questioned in regards of previous results confirmed by ours in this study.

本研究旨在考虑自我决定理论描述的不同调节类型，检验学生动机在学生自我概念和成就之间的中介作用。我们研究的中心目标是确定不同学校科目的自主和受控动机类型是否会以不同方式调节自我概念和成就之间的关系。事实上，自主动机类型已被证明比受控动机类型与学业成果更相关，因此我们预计这将导致不同的中介效应。对 411 名 9 年级和 10 年级高中生进行了 2 波研究。学生的自我概念、自我决定动机和成绩在 4 个不同的学校科目（即数学、法语、英语）中进行了评估, 体育）。结果证实了我们的假设，并表明自主动机类型介导了自我概念对相应学校科目成绩的贡献，而受控动机类型则不然。讨论了教育和方法论的影响，并根据我们在本研究中证实的先前结果，对内射方法调节在相对自主连续体上的定位提出了质疑。