Dementia is a relatively “new” disease in the medical field. Over the past few decades, neurologists, geriatricians, psychologists, and sociologists were keen to determine the causes of dementia. The prevalent picture of the scientific and theoretical causation of dementia, however, overshadows the lay perspective of dementia. To get a better understanding of the latter aspect, this study examined family carers' knowledge of dementia and how they made sense of the disease. Individual interviews were completed with 18 family carers. The interview data were analyzed based on grounded theory, which is characterized by a constant comparative method of analysis (Glaser & Strauss, 1967). This method of analysis is inductive in nature and allows the construction of a theory of the lay interpretation of dementia. The study revealed family carers' limited knowledge of dementia might be related to medical professionals' inadequate explanations of the multifaceted dimensions of dementia. Hence, the family carers tended to use external events and personal experiences to explain the occurrence of dementia. Findings suggested that the development of a lay understanding of dementia was a means for family carers to gain control of this abstruse disease and served as an adaptive strategy to cope with the loss experienced during the caring process. The study indicates a definite need for health care professionals to form partnerships with family carers in order to develop good dementia care.