As teachers modify their instruction to meet English Language Arts (ELA) Common Core State Standards (CCSS), how do these modifications influence literacy instruction and learning opportunities afforded to students? While the CCSS standardized objectives for literacy instruction, the enacted curriculum is uniquely shaped by teachers and their students (Coburn, 2001; Datnow & Castellano, 2000; Smagorinsky, Lakly, & Johnson 2002). This study describes how two elementary school teachers in one school: (a) perceived the ELA CCSS and their influence on instruction and the enacted curriculum; (b) adapted and aligned literacy instruction to respond to implementation of the CCSS; and (c) created instruction and literacy learning opportunities influenced by the ELA CCSS. To investigate the rich, nested levels of context in which teachers used the ELA CCSS to construct literacy instruction and learning opportunities for children, I applied a sociocultural framework and Engestrom's third generation Cultural Historical Activity Theory (CHAT) model to create a theory-driven description of how teachers approached CCSS implementation and literacy instruction. Case study and CHAT methodologies were used to address the questions focused on instructional implementation of ELA CCSS and literacy learning. I analyzed data from interviews, observations, and documents through grounded theory's constant comparative analysis (Charmaz, 2006) to uncover specific themes related to CHAT. Once I identified activities based on my constant comparison analysis, I performed a CHAT analysis on the selected activities (Yamagata-Lynch, 2010). Findings from this study provide information about the implementation of the ELA CCSS in literacy instruction and the enacted literacy curricula. Findings suggest that multiple levels of context influenced the ELA CCSS implementation, including teachers' perceptions (Coburn, 2001; Maloch & Bomer, 2012). They also suggest that while teachers may teach from a standardized curriculum, the literacy learning opportunities differ in each class (Pacheco, 2010). [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]