To develop and validate scales for reliably assessing dementia and urinary incontinence knowledge of older adults in the community. Items were generated through a literature review, refined through a Delphi study ( n = 19), and then revised through a pilot study ( n = 29). Item analysis and exploratory factor analysis were applied to finalize the scales ( n = 244). Construct validity, reliability, and acceptability were evaluated ( n = 243). The two knowledge assessment scales for dementia and urinary incontinence, respectively, comprised 12 items and 8 items. Model fit indicators of both met the criteria of confirmatory factor analysis. Cronbach’s α were .82 and .70, respectively. Completion ratio and completion time of the two scales was 83.51% and 4.22 ± 1.90 minutes. The knowledge assessment scales for dementia and urinary incontinence with satisfactory validity, reliability, and acceptability, could be served as valid tools for disease prevention and management among older adults in the community.