To assess the causal attributions for losing perceived by both early and late adolescents, a sample of 150 high school students responded to a questionnaire comprising three categories of activities (sport, academic, and social) in which they had not won or achieved a desired outcome. The obtained attributions for not winning were categorized into four areas: task difficulty, luck, effort, or ability. Adolescent girls indicated significantly more internal attributions and boys more external attributions. Seventh graders' attributions were external and twelfth graders' were internal. No differences emerged as a function of high and low self-esteem. Implications for the structure of achievement tasks are discussed.