Purpose: The purpose of this study is to examine the effective social justice instructional leadership practices of leaders in schools implementing the International Baccalaureate (IB) Primary Years Programme (PYP) and identify challenges and barriers these leaders experience when implementing social justice instructional leadership. Framework: Social justice instructional leadership (SJIL) includes: (a) establishing vision to promote a safe and inclusive environment, (b) facilitating high-quality learning experiences with an engaging curriculum that includes multiple perspectives, (c) building capacity of the entire school community to positively impact achievement, (d) creating a supportive organization for all stakeholders, and (e) collaboration with external partners for innovation, support, and resources. Methods: This qualitative case study employed interviews and examination of documents to identify the effective SJIL actions of school leaders and the challenges these leaders experienced in IB PYP schools in one urban, southeastern school district. Deductive and inductive analysis techniques helped categorize emergent themes related to effective practices and challenges. Findings: The findings of this study present actions that PYP leaders identified as having a positive impact on the social-emotional and academic growth of students in traditionally marginalized groups including developing a culturally responsive environment, providing access to learning in inclusive and diverse settings, building a data driven culture, fostering relationships, and educating stakeholders. The findings also provide suggested strategies for overcoming roadblocks to SJIL including providing intensive teacher support, implementing targeted professional learning, educating parents, soliciting support through outreach, and partnering with organizations for wrap-around services. Implications: The findings of this inquiry suggest that to develop school cultures that promote institutional access, educational equity, and academic success for all students, school leaders must be deliberate when: hiring and developing teachers, budgeting, and implementing resources, practices, and protocols. This study also reinforces the need for providers of educational leadership training to include SJIL practices, methodologies, and competencies in leadership programs. Finally, the results of this study support the need for states and districts to change education funding formulas based on the needs of students to enable districts and schools to serve their neediest children with fewer barriers.