This study looks at the impact of first language (L1, or “mother tongue”) complexity on reading achievement in the Philippines using Grade 3 Early Grade Reading Assessment (EGRA) data collected in 2013 and 2019. EGRA data were collected from 232 schools in 2013, when students learned to read in the national languages of Filipino and English. These data on English and Filipino performance were collected again in the same schools in 2019, when students would have, according to policy, learned to read first in their mother tongue.