Despite the increasing ethnic diversity of England's school-age population, academic literature on ethnic school segregation remains small, dated and hindered by methodological challenges. This study seeks to address these issues by measuring ethnic school segregation between 2006-2019 using two methodological innovations. Firstly, it is the first national study in England to adopt a multi-group segregation index to measure segregation between five major groups in a single concise metric. Secondly, it uses a clustering algorithm to group local schools into 'pseudo-neighbourhoods', which allows for segregation to be measured within local educational markets. The article shows that between 2006 and 2019 the median level of ethnic school segregation within English pseudo-neighbourhoods fell by 25%, which suggests students from different ethnic groups have become more evenly spread across local schools. Additionally, areas in the North of England were typically found to have higher levels of segregation than those in the South.