This research investigates English as an additional language or dialect (EAL/D) policy interpretation and implementation in schools by principals and EAL/D teachers in one Australian educational jurisdiction. This is an important investigation because the way EAL/D policy is presented by education departments, and the way it is approached and managed within schools determines how fair and equitable services are for EAL/D students. EAL/D students need specific English language learning support in order to learn English for educational purposes. EAL/D policy directs the processes for EAL/D programs, but varied interpretation and implementation can mean actions fail to achieve the policy’s intent. Therefore, it is important to know how principals and EAL/D teachers view, approach and engage with EAL/D policy, and to whom they look for advice. A multi-site case study approach was used to investigate the question ‘How is English as an additional language or dialect policy interpreted and implemented by principals and teachers?’ Principals and teachers were interviewed in 17 primary schools within the selected educational jurisdiction. The research identified five key elements that affected EAL/D policy interpretation and implementation. These were leadership strategy, EAL/D policy intent and relevance, staffing, specialist EAL/D qualifications, and colleague support. In terms of leadership strategy, findings reveal people who take an EAL/D leadership role in the school affect policy implementation. The level of responsibility supervisors distributed to them determined how much influence they had within the school. Principals and teachers perceived EAL/D policy as non-mandatory, or soft, which raised questions about policy interpretation, compliance, accountability, expectations, and ultimately policy implementation. Principals either struggled to find qualified teachers or disregarded the need for specialist qualifications positioning EAL/D teacher qualifications as a contentious issue. Generalist-qualified teachers in an EAL/D role were faced with challenges their EAL/D qualified colleagues were not, further contributing to rhetoric about teacher qualification, efficacy and effectiveness. Colleagues were an important point of support for both policy interpretation and implementation. Three models of policy implementation emerged from findings. These each reflected the five key elements and were labelled the Stars Aligned model, the Missing Links model, and the Perfect Storm model. The Stars Aligned model reflected the ideal, where all key elements were positively employed. This model was not fully present in practice. The Missing Links model was common in practice, where interpretation and implementation practices fell short of the ideal. The Perfect Storm model was identified in practice and reflected the worst-case scenario where all key elements were either lacking or not addressed at all. The models represent points along a continuum. The link between the models and findings from the research made it possible to identify changes in practice and identify ways EAL/D policy implementation could be evaluated and improved. Therefore, an appraisal tool was developed with guides to practice. It is recommended education departments and schools use this appraisal tool as a means to evaluate and improve EAL/D policy implementation, engagement and support provision.