Vietnam's Ministry of Education and Training issued a new general education curriculum and Getting-to-know-English for Grades 1 and 2. Teachers are crucial to implementing Getting-to-know-English for Grades 1 and 2. However, teacher agency has been understudied, despite recent studies in Vietnam. These studies examined teacher agency in executing the language policy, the pilot English program under the National Foreign Language Project 2020. Little study has been done on how teachers use the Getting-to-know-English in Grades 1 and 2. The current study, based on the ecological approach, seeks to understand how Vietnamese primary teachers utilize the Getting-to-know-English for Grades 1 and 2. Documents and interviews provided data. Data analysis showed that teachers adapted teaching activities and resources, accepted and resisted assessment methods and lesson planning, accepted teaching methods, and accepted and adapted teaching content. Prior professional knowledge and experience, curriculum map and evaluation, students' learning styles, resources, and professional development program affected teacher agency enactment. The study advises more professional training programs for teachers to implement the Getting-to-know-English for Grades 1 and 2.