In the ongoing effort to improve standards-based instruction in the nation's urban public schools, the Council of the Great City Schools published a second edition of "Supporting Excellence: A Framework for Developing, Implementing, and Sustaining a High-Quality District Curriculum." This document is designed to help districts: (1) Determine the quality and alignment of instructional guidance to clarify the district's learning expectations at each grade-level with a focus on student assets and diverse learners; (2) Ensure that instructional materials for English language learners, students with disabilities, and historically marginalized students are rigorous and aligned to district standards; and (3) Provide targeted professional development for teachers, principals, and district staff. Teaching and learning have changed substantially in recent years, driving the demand for more responsive curricular materials and guidance to help teachers address unfinished learning, boost student engagement, and meet the social emotional and mental health needs of students. While these learning necessities are not new, the pandemic served to highlight their fundamental role and connection to academic outcomes. Furthermore, the pandemic exposed the significant systemic and structural barriers to learning faced by marginalized populations and diverse learners that have been present for decades. These factors included physical barriers, such as a lack of proficiency or access to technology and the Internet, as well as barriers such as low expectations, limited communication between communities and schools, and outdated or culturally inappropriate curricular materials that limited student access to rigorous, grade-level instruction. This second edition provides instructional leaders and staff with a core set of criteria for what high-quality district curriculum guidance must entail in today's educational environment in order to ensure all of the school children meet the highest standards and become successful and productive members of society. With the help of instructional leaders from urban districts and guidance from an expert panel, this edition has included additional key features with annotated exemplars from the member districts that reflect a focus on addressing unfinished learning during Tier I instruction, incorporating social and emotional learning, supporting culturally-relevant instruction, effectively employing instructional technology, and addressing inequities in access to grade-level instructional rigor. This second edition also provides actionable recommendations for developing, implementing, and continuously improving upon a district's curriculum, ensuring that it reflects shared instructional beliefs and high expectations for all students throughout the district.