In Thailand, a series of policies have been implemented at all levels of Thai education. It is hoped that English language ability among Thai citizens will be improved. In primary education, following the English language education policy for primary school students introduced by the Office of Basic Education Commission (2016), English has been introduced to first graders onwards. They study English one hour every day, five days a week. When they finish grade 6, they should demonstrate their language ability at a CEFR A1 level. Various English tests have been used to check if the students are either proficient or able to achieve the learning goals. These tests include teacherprepared tests at the classroom level and the Ordinary National Tests, or O-NETs, at the national level. Essentially, the O-NETs are administered to the sixth, ninth and twelfth graders. Interestingly, although the CEFR has been implemented in our educational system, O-NETs test scores have not been aligned with CEFR. This research project focused on developing a local English language proficiency test for young learners. In this article, key considerations, and challenges in the process of developing the test are presented and discussed. It is hoped that the presentation and discussion are timely and beneficial for those planning to develop their own tests for use in their own contexts.