The purpose of this study was to investigate mastery goal states that students might spontaneously adopt in individual lessons. Interviews were carried out with 32 grade 10 students, who were asked about a recent lesson they had experienced. Responses indicated that positive mastery goal states could be represented by a situated and dynamic feeling of “wanting to learn”. However, students also reported a feeling of “not wanting to learn”. This latter form did not fit any of the existing dimensions of achievement goals, so it was decided to refer to it as a negative mastery goal state. The positive and negative dimensions were educationally significant because they were highly correlated with students’ self-reported learning behaviors during that lesson.