Although students' affects and behaviors in achievement situations have been shown to be influenced by their previous learning experiences, less is known about how they relate to students' dispositional characteristics, such as temperament. This study examined to what extent children's temperament is related to their affective and behavioral responses in achievement situations. Teachers rated first-graders' (n = 153) temperamental characteristics in the Fall semester. Children's active task avoidance, anxiety, and helplessness were rated in test situations in the Fall and Spring semesters. The results showed that the more easily distracted the children were, the more task avoidance they showed, and the more their task avoidance increased during the first grade. Moreover, children's high level of inhibition was related to high levels of anxiety and helplessness. The findings suggest that characteristics that are related to students' behavioral regulation and inhibition are particularly important for their affective and behavioral responses in achievement situations. (Contains 3 figures and 1 table.)