The purpose of this study was to examine different approaches to assessing implementation in an early childhood curriculum research study. Early childhood teachers in 51 preschool classes located at nationally dispersed sites implemented the Children's School Success curriculum for a school year. Structural (proportion of curriculum delivered) and process (quality of delivery of curriculum) measures of implementation were collected for the literacy, math, and social components of the curriculum. Also, a multiplicative composite score incorporating information from the structural and process measures was calculated. Site differences occurred for the process measure, but not the structural and composite measures. Analysis of the process implementation measures collected across time revealed primarily stable trends across sites. Significant associations were found between measures of implementation and some of the child outcome variables, with the different forms of implementation associated with different outcome variables. (Contains 5 tables and 1 figure.)