The School District of Philadelphia (SDP) serves a diverse student population, and language is a key dimension of this diversity. Students enrolled in District-run schools in 2021-22 speak 155 different languages at home, and the number of English Learners (ELs) in the District is growing.

However, linguistic diversity is not distributed uniformly across schools, and some schools serve students with a much wider variety of linguistic backgrounds than others, requiring different resources and support strategies as a result.

The Office of Research and Evaluation has developed a new indicator to better describe the predominant composition of the EL population at a given school. The SDP Linguistic Diversity Indicator (LDI) is a calculation of the number of home languages required to account for 80% of English Learners in a given school or population.

This focus brief describes how the LDI is calculated and discusses potential applications of the new indicator.