BACKGROUND: There is a growing interest in studying the influence of child-care center policies on the health of preschool-aged children. OBJECTIVE: To develop a reliable and valid instrument to quantitatively evaluate the quality of written nutrition and physical activity policies at child-care centers. DESIGN: Reliability and validation study. A 65-item measure was created to evaluate five areas of child-care center policies: nutrition education, nutrition standards for foods and beverages, promoting healthy eating in the child-care setting, physical activity, and communication and evaluation. The total scale and each subscale were scored on comprehensiveness and strength. SETTING: Analyses were conducted on 94 independent policies from Connecticut child-care centers participating in the Child and Adult Care Food Program. STATISTICAL ANALYSES PERFORMED: Intraclass correlation coefficient was calculated to measure inter-rater reliability, and Cronbach's α was used to estimate internal consistency. To test construct validity, t tests were used to assess differences in scores between Head Start and non-Head Start centers and between National Association for the Education of Young Children-accredited and nonaccredited centers. RESULTS: Inter-rater reliability was high for total comprehensiveness and strength scores (intraclass correlation coefficient=0.98 and 0.94, respectively) and subscale scores (intraclass correlation coefficient=0.84 to 0.99). Subscales were adequately internally reliable (Cronbach's α=.53 to .83). Comprehensiveness and strength scores were higher for Head Start centers than non-Head Start centers across most domains and higher for National Association for the Education of Young Children-accredited centers than nonaccredited centers across some but not all domains, providing evidence of construct validity. CONCLUSIONS: This instrument provides a standardized method to analyze and compare the comprehensiveness and strength of written nutrition and physical activity policies in child-care centers.