This investigation was designed (l) to assess to what causal factors Brazilian elementary students attribute their success or failure in achievement tasks; (2) to verify whether their attributions can be classified into the categories proposed by Weiner (1972): ability, effort, task difficulty, and luck; and (3) to assess the relationship between academic achievement, attributional patterns and self-concept. The subjects in the two studies consisted of 237 low socioeconomic status fourth grade students classified as having satisfactory (SP) and unsatisfactory (UP) academic performance. Study one showed that students' attributions can be classified into the four causal factors. In study two, subjects were administered a self-concept test, two mathematics, and two Portuguese tests. Asked to assign causality to their outcome, most of them attributed their success to effort. SP students externalized their failure and UP students internalized it. SP students had significantly higher self-concept scores. Results suggest that students with a history of academic success feel more capable to perform well than children with a history of failure. The latter do not believe in their ability to succeed. (Author/HOD)