Background: The challenge of an aging population with its expected attendant problem of an increase in the number of people with dementia is a growing concern across the world. Objective: The aims of this study were to establish the prevalence and risk factors of dementia in Singapore among the elderly resident population (aged 60 years and above). Methods: The WiSE study was a comprehensive single phase, cross-sectional, epidemiological survey that adapted the 10/66 protocol to establish the 10/66 and the Diagnostic and Statistical Manual of mental disorders -fourth edition (DSM-IV) diagnosis of dementia. 10/66 and DSM-IV dementia diagnosis as established by the survey questionnaires was validated by comparing against a gold standard of clinical assessment. Results: A total of 2,565 respondents completed the study giving a response rate of 65.6%. The validity of 10/66 dementia was higher (sensitivity = 95.6%, specificity = 81.8%) than that of DSM-IV dementia (sensitivity = 75.6%, specificity = 88.6%) when compared against the clinical gold standard. The study found that the prevalence of 10/66 dementia was 10% in the older adult population while the prevalence of DSM-IV dementia was 4.6%. Older age (75 years and above); no formal education, or completed primary education (versus higher education); homemaker and retired status (versus employed); and a history of stroke were associated with a higher risk of 10/66 dementia. Conclusion: The establishment of accurate data on the number of people with dementia is essential in the planning of services and initiatives.