Ageism (prejudice against older persons) is the third great “ism” of Western contemporary society, along with racism and sexism. Age-based discriminations intersect with other power relations, such as race, class and gender. Precisely, the term “gendered ageism” covers the intersectionality of age and gender bias. The effects of this phenomenon are pervasive and harmful, especially on older women regarding their recruitment, career opportunities and pensions. Among the various ontological perspectives, post-humanism sees ageism as performed through the material world and human practices. Material gerontologists and feminist gerontologists have contributed to questioning the binaries of decline and success surrounding the ageing body and have proposed to move towards an idea of it as a proliferative and productive force of positive difference. Interventions against age- and gender-based discriminations require multiple and combined efforts promoting the collaboration of science and society and dialogue between experts.