Research on optimistic attributional style (OAS) has focused primarily on the relations of style with high well-being and low depression (Peterson et al., 1985; Sweeney et al., 1986; Hu et al., 2015). Less research has focused on the relationship between OAS and achievement. Also, the extant achievement research has concentrated on optimism following negative events rather than optimism following positive events, and has yielded a rather mixed picture. Via both a meta-analysis and two new studies, we examined the relationship between OAS, academic performance and well-being. In the meta-analysis, dispositions to make stable and global attributions for positive events were more strongly related to academic achievement (d = 0.21, k = 30, N = 6351) than dispositions to make unstable and local attributions regarding negative events (k = 66, d=0.11, N = 11023). Type of test (general vs. achievement-specific) and academic level moderated the associations. Two new studies with schoolchildren and university students were designed to address remaining questions. In both studies structural equation modeling results indicated a positive relationship between OAS for positive events in achievement situations and academic performance, including boosted achievement over time. Practical recommendations for the development of OAS for positive events are provided.