Nearly half of Singapore's 3,034 nationally representative survey respondents reported experiencing age-based discrimination, with the youngest (21-30 years) and oldest (71+ years) groups showing 1.5 points higher ageism scores on the WHO scale. Lower socioeconomic status, particularly education level, increased discrimination experiences by approximately 1 point. Most significantly, individuals who perceived themselves as older than their chronological age faced substantially higher discrimination rates. This U-shaped age distribution challenges common assumptions that ageism primarily targets older adults. The finding that subjective age perception—feeling older than one's actual years—was among the strongest predictors suggests ageism operates through complex psychological mechanisms beyond simple chronological bias. Singapore's 49.4% prevalence aligns with global patterns, indicating ageism is a universal health determinant rather than a culturally specific phenomenon. The research establishes ageism as a significant public health concern requiring intervention across the lifespan, not just in later years. However, the cross-sectional design limits causal inferences about whether ageism accelerates subjective aging or vice versa. This represents foundational epidemiological work that should inform Singapore's aging society policies, though longitudinal studies are needed to understand ageism's health trajectory impacts.