Objective To compare the psychometric properties of four measures of dementia institutional knowledge. Methods Fifty‐eight dementia care staff completed the Dementia Knowledge Assessment Tool Version Two (DKAT2), Alzheimer's Disease Knowledge Test (ADKT), Alzheimer's Disease Knowledge Scale (ADKS) and Dementia Knowledge Twenty (DK‐20). The convergent validity and reliability of each measure were examined. Results The level of dementia knowledge in this sample was similar to that reported in comparable surveys. The ADKT, DKAT‐2 and DK‐20 had marginal to acceptable internal consistency (α ≥ 0.67), and the ADKT, DK‐20 and ADKS were positively correlated with each other (r's = 0.45–0.60), demonstrating convergent validity. The DKAT2 had lower intercorrelations with the other measures (r's = 0.32–0.45). The ADKS had poor internal consistency (α = 0.29). Conclusion As the first head‐to‐head comparison of these tests in a single sample, this study should assist clinicians and researchers to select a dementia knowledge test.