This study considers the roles of managerial ageism and causal attributions in the age bias process. Specifically, we predicted that employee age and manager ageism would interact in predicting the severity of recommendations made about an employee's performance errors, such that ageist managers would be more likely to engage in age bias. Second, we proposed that age bias is caused partially by differential attributions made about the performance errors of older vs. younger workers. Results indicated that older employees received more severe recommendations for poor performance than did their younger counterparts. Also, some ageist attitudes moderated the relationship between age and performance recommendations. Stability attributions mediated the relationship of employee age on endorsement of the more punitive recommendations.