The present study aimed to develop and validate a questionnaire assessing parents' beliefs about, and attitudes toward, supporting young children's English as a second/foreign language development -- Parent English Language Belief and Attitude Questionnaire (PELBA-Q). The PELBA-Q was piloted with 173 parents of kindergarten-aged children and further validated with a sample of 278 parents in Hong Kong. A series of exploratory factor analysis and confirmatory factor analysis was conducted to explore the factor structure and evaluate model fit, which resulted in a 20-item questionnaire with four factors (i.e. Perceived Importance of the Home Environment; Perceived Child's English Language Ability and Self-Efficacy; Normative Beliefs; and Control Beliefs). The convergent and divergent validity of the PELBA-Q were also established by examining the relationship between the PELBA-Q and parents' home practices and family characteristics. The PELBA-Q had satisfactory model fit indices and demonstrated good reliability and validity. The findings showed that the PELBA-Q could potentially be used as a sound assessment tool for measuring parents' beliefs and attitudes on young children's English as a second/foreign language development and could contribute to greater understanding of how parental beliefs and attitudes may influence home practices and children's English language learning outcomes.