The Common Core State Standards (CCSS) potentially shifts the way US schools approach teaching and learning. Research suggests that it is important to understand how educators view the CCSS and how they believe the CCSS may impact their practice. We developed and tested an instrument to investigate educator beliefs about the implementation of CCSS. We collected data from two samples of educators regarding their beliefs about the CCSS in mid-size school districts in California that had begun to introduce the CCSS. Our results indicate that the instrument consistently measured three interrelated, yet distinct, sub-constructs of educator beliefs about the CCSS implementation and that the sub-constructs are statistically significantly associated with trust, professional knowledge, and the pattern of CCSS-related professional interaction.