Two survey instruments were developed and validated to measure early childhood teachers' (1) knowledge of early mathematical development and (2) beliefs about mathematics teaching and learning in the preschool classroom. The Knowledge of Mathematical Development (KMD) Survey was designed to measure teachers' knowledge of mathematical development of young children. The Beliefs Survey was designed to measure beliefs concerning (a) age-appropriateness of math instruction; (b) classroom locus of generation of mathematical knowledge; (c) math vs. socioemotional development as primary goals of preschool education; and (d) comfort level in providing that instruction. Validity of the instruments was supported through construct, content and concurrent measures of validity. Methods included cognitive interviews, literature reviews, and interviews with experts in the field, as well as statistical procedures such as analyses of variance between well-defined groups of in- and pre-service teachers, and correlations between measures of knowledge and beliefs. Reliability of both instruments was examined through the use of Cronbach's alpha and item-total correlations. These statistical procedures provided good to excellent support for both validity and reliability. Potential applications include evaluation of the impact of early childhood education teacher preparation programs and professional development interventions.