The relations between effortful control, emotionality (anger, sadness, and shyness), and academic achievement were examined in a short-term longitudinal study of 291 kindergartners. Teachers and parents reported on students' effortful control and emotionality. Students completed the Continuous Performance Task and the Letter-Word, Passage Comprehension, and Applied Problems subtests of the Woodcock-Johnson tests of achievement. Effortful control was positively related to achievement. Parent- and teacher-reported anger and teacher-reported sadness and shyness were negatively related to achievement, but many of the main effects were qualified by interactions with effortful control. At low levels of anger or sadness, students high in effortful control performed best, but at high levels of these emotions, all children performed similarly. (Contains 2 footnotes, 2 tables, and 1 figure.)