This study explored the language assessment literacy (LAL) level and language testing and assessment (LTA) needs of 57 English teachers at senior high school level in Taiwan. An LAL test, three quantitative questionnaires and a qualitative survey were administered, conveying the overall LAL level and LTA needs of the participants. The qualitative survey then elicited their perceptions of and perspectives on classroom-based assessments and national high-stakes tests with regard to a newly implemented national curriculum (i.e., 108-Curriculum). The results show that the teachers lack adequate LAL to varying degrees, depending on their demographic background. Additionally, the participants identified some assessment topics, from large standardized testing to applying test results. They also reported their greatest training needs: providing feedback, finding teaching content, and assessing integrated skills. The teachers' qualitative accounts generated five themes, from education in testing and assessment as a useful tool to the gap between classroom-based assessments and the national tests. The results not only refine assessment modules in the teacher education programme but suggest a direction for the assessment training of English teachers. The study concludes by suggesting future LAL investigations in the English-teaching context of Taiwan or wider international communities.