For many Japanese, fear about senility is not primarily expressed in relation to pathological conditions like Alzheimer's Disease (AD). Instead, as people grow older, their concern focuses on a widely recognized category of decline in old age which, although symptomatically and conceptually overlapping with AD and other forms of senile dementia, is distinguished from unambiguously pathological conditions. This article examines the meaning and experience of this condition, known as boke, and shows that senility in Japan is culturally constructed in a way distinct from the clinical biomedical construction of senility-as-pathology which has become increasingly the norm in North America. Rather than being a disease, boke is viewed as an illness over which people are believed to have some degree of agency in relation to its onset - through activity, particularly within the context of groups, it may be prevented or at least delayed. The data discussed also suggest the importance of culture in defining the meanings of normal or abnormal aging. While from a clinical perspective it may be clear where the line is to be drawn between what is normal and what is pathological aging, from the perspective of older people, the basis of what is considered normal or abnormal aging may not have a direct link to disease.