This article reports on the development, internal consistency, and reliability of a new preschool and kindergarten classroom observational measure based on NAEYC's Guidelines for Developmentally Appropriate Practices. The Classroom Practices Inventory (CPI) is a 26-item rating scale tapping the curricular emphasis and emotional climate of programs for 4- and 5-year-old children. The scale demonstrates a high degree of internal consistency. Over half the measure's variance is accounted for by a factor tapping encouragement of curiosity, creativity, and provision of concrete materials. In a study of 10 preschool programs, CPI scores correlated significantly with teachers' and parents' educational attitudes. Modest relationships were found between the CPI scores of children's preschools and measures of academic skills, creativity, and anxiety. It is concluded that the CPI appears to be a promising measure for examining developmentally appropriate practices in early childhood education, especially programs providing formal academic learning experiences. The wide range of scores and their association with other school, parent, and child variables indicate that the CPI is sensitive to important differences in curriculum and teaching practices in early childhood programs. (RH)