Ageism as perceived by older individuals has been recognized as a potential risk factor for physical and mental health. We aimed to develop a comprehensive scale that can quantify perceived ageism among aging individuals (55+), including both positive and negative stereotypes, prejudices, and discriminations. This effort resulted in an 8-item Perceived Ageism Questionnaire (PAQ-8), with good psychometric properties and a two-factor structure distinguishing a positive (3 items) and negative (5 items) subscale (Analysis 1; n = 500). This dimensionality was confirmed in a separate cross-validation sample (Analysis 2; n = 500). The subscales’ correlation patterns with individuals’ self-perceptions of aging and mental health variables (i.e., quality of life, mental well-being, depression, anxiety, loneliness and perceived stress) accorded with theoretical hypotheses and existing knowledge of the concept of ageism. The PAQ-8 can help to gather more standardized data of the level, role and impact of perceived ageism.