Drawing on theories of stereotype content and role congruity, this research investigated the role of stereotypes for employment discrimination against older candidates. Study 1 investigated the content of stereotypes about older workers, focusing on warmth and competence as the two core dimensions in social judgement. As predicted, older workers were perceived as less competent but warmer than younger workers. Studies 2 and 3 investigated how these stereotypes interact with job requirements to predict age bias in an experimental setting. Further, they tested if warmth- and competence-related stereotypical inferences mediate the relation between candidate age and selection bias. Results showed that age bias was robust. Older candidates were discriminated against, even if the job primarily required warmth-related qualities, and independently of evaluators' own age or professional experience in human resources. Moreover, age bias was mediated by competence-related stereotypical inferences. Age bias was also mediated by inferences related to warmth but those inferences were opposite to the high-warmth older worker stereotype identified in Study 1. Implications of the findings for theoretical approaches to age discrimination and for organizational practice designed to combat age discrimination are discussed.