Seattle World School has open enrollment and accepts non-English-speaking students throughout the academic year.  Each year between 500 and 600 children attend the school, with close to 400 students as of Spring 2017. These young people come from all over the world, particularly from centers of conflict in developing countries.  At any given time between 35 and 40 different languages and dialects are spoken at the Seattle World School.

Currently, Spanish speaking students from Central America, Mexico, and South America form the largest language group.   The proportion of students from Asia and Africa changes regularly, with new arrivals daily.