This study investigated whether girls' and boys' perceptions of their teacher may explain gender-related difference in academic motivation. One hundred and twenty-nine ninth-grade Israeli students (67 males and 62 females) completed a questionnaire designed to assess their motivation to learn, their affect while studying in school, and their perception of their teachers' behaviors. The results indicate that girls tend to perceive their teacher as more supportive than do boys and that this perception mediates gender-related differences in motivation and emotional experience. This finding suggests a mechanism to explain gender-related differences in motivation and highlights the importance of investigating those characteristics that can affect student perception of the teacher as supportive. Beyond the known contribution of the need for a supportive environment, knowledge of such characteristics can help promote adaptive motivation.