BACKGROUND: Thailand is experiencing a rapid increase in the number of older people with dementia (PWD). We examined the frequency, severity, and correlates of dementia neuropsychiatric symptoms (NPS) among community-dwelling Thai older adults. METHODS: This study was based on analysis of baseline data from a larger clinical trial comparing two different implementation approaches of an evidence-based exercise intervention for people with dementia. To be eligible, participants needed to be age 60 and above, have probable dementia, have one or more NPS, be ambulatory, and have an adult (age 18+) family caregiver. In the 353 eligible participants, we examined the correlation between NPS severity and caregiver distress (assessed by the Neuropsychiatric Inventory Questionnaire or NPI-Q) and used ordinary least squares (OLS) regression to examine associations between PWD and caregiver characteristics and NPS severity. RESULTS: NPS frequency varied from 18% for appetite and/or eating changes to 42% for delusions. NPS severity was significantly (p <0.05) associated with caregiver stress for all individual NPS. Among PWD characteristics, higher ADL score (less functional impairment) was inversely associated with NPS total severity (b = -0.16, p <0.05). More physical role limitation was significantly associated with higher NPS total severity (b = 0.77, p <0.001). Among caregivers characteristics, higher burden was significantly associated with higher NPS total severity (b = 0.19, p <0.001). CONCLUSION: Our study found NPS to be common among community-dwelling PWD in Thailand and have adverse impacts on both PWD and family caregivers. These findings highlight the clinical importance of NPS symptoms among Thai older adults.