Primary caregivers' child oral health care beliefs and practices are major factors in the prevention of Early Childhood Caries (ECC). This study assessed the validity and reliability of a newly-developed scale--the Early Childhood Caries Perceptions Scale (ECCPS)--used to measure beliefs regarding ECC preventive practices among primary caregivers of young children. The ECCPS was developed based on the Health Belief Model. The construct validity and reliability of the ECCPS were examined among 254 low-socioeconomic status primary caregivers with children under five years old, recruifed from 4 Bangkok Metropolitan Administration Health Centers and a kindergarten school. Exploratory factor analysis (EFA) revealed a four-factor structure. The four factors were labeled as Perceived Susceptibility, Perceived Severity, Perceived Benefits and Perceived Barriers. Internal consistency measured by the Cronbach's coefficient alpha for those four factors were 0.897, 0.971, 0.975 and 0.789, respectively. The ECCPS demonstrated satisfactory levels of reliability and validity for assessing the health beliefs related to ECC prevention among low-socioeconomic primary caregivers.