The purpose of our study was to examine elementary literacy teachers' perceptions of their preparedness to implement the ELA CCSS [English Language Arts Common Core State Standards]. We defined preparedness across three dimensions: teachers' perceived levels of knowledge of the standards and its components; efficacy to implement changes; and actual changes to their instructional practices. A survey was developed based on the literature and administered to 158 elementary school teachers in two districts. Findings document the nature of their professional development and identify areas where additional development opportunities are necessary. While all teachers reported receiving professional development on the ELA CCSS, they varied in knowledge ratings across various dimensions of the standards, self-efficacy ratings, and the degree they reported implementing changes in their practice with the introduction of the ELA CCSS. Discussion focuses on the need to provide more time and supports to teachers as they deal with the challenges of the new standards.