Until recently, there was no dementia screening tool for Indigenous Australians and a paucity of information on the extent of dementia in Indigenous Australians. This thesis describes the development and validation of a tool to assess cognitive impairment in remote Indigenous Australians with the primary purpose of determining the prevalence of dementia and other associated conditions in this population. The tool was reevaluated with the larger prevalence sample and a short version of the tool was developed and evaluated. The Kimberley Indigenous Cognitive Assessment (KICA) tool was validated with Indigenous Australians aged over 45 years from the Kimberley region of Western Australia (n=70). The results were later confirmed in a larger sample from the remote Kimberley (n=363), and an additional sample in rural and remote areas of the Northern Territory (n=47). The KICA results were compared to independent consensus diagnoses using DSM-IV and ICD-10. Interpreters were used whenever participants were not proficient in English. These data led to the determination of a cut-off score of 33/34 out of a possible total score of 39 for the cognitive component of the KICA (KICA-Cog), with a sensitivity of 0.93 and specificity of 0.95 and AUC of 0.98. The tool is now widely used within remote areas of Australia. A short version of the KICACog (sKICA-Cog) was developed and found to be a valid brief screening tool for dementia in the Kimberley population, and had a cut-off score of 20/21 out of a possible 25, with a sensitivity of 0.89, specificity of 0.95 and AUC of 0.98. The sKICA-Cog should be used in combination with the KICA cognitive informant questionnaire (KICA-IQ). The KICA-IQ cut-off score of 2/3 out of a possible 16 was determined, with a sensitivity of 0.76 and specificity of 0.84 and AUC of 0.91. Using the validated KICA, the prevalence of dementia and cognitive impairment not dementia (CIND) was determined in a semi-purposive sample consisting of 363 Indigenous Australians aged over 45 years from 6 Aboriginal communities and one town in the Kimberley region. Participants were screened with the full KICA and 165 participants had an independent specialist review with consensus diagnoses. The prevalence of dementia was 12.4%, 5.2 times greater than the Australian prevalence of 2.4%, after age adjustment. The prevalence of CIND was 8.0%. Characteristics associated with dementia included older age, male gender (OR 3.1, 95% CI 1.4, 6.8), no formal education (OR 2.7, 95% CI 1.1, 6.7), smoking (OR 4.5, 95% CI 1.1, 18.6), previous stroke (OR 17.9, 95% CI 5.9, 49.7), epilepsy (OR 33.5, 95% CI 4.8, 232.3) and head injury (OR 4.0, 95% CI 1.7, 9.4). Other factors associated with dementia included incontinence, falls and poor mobility. The KICA is a valid assessment tool for rural and remote Indigenous Australians. The prevalence of dementia amongst Indigenous Australians is substantially higher than generally found in non - Indigenous Australians and other populations in the developed and developing world.