This study investigates the Central Highland EFL teachers’ language proficiency
maintenance since they finished the formal training workshops held by authorized
universities. EFL teachers’ perceptions of the necessity and effectiveness of the national
large-scale English language proficiency training to their teaching was explored. Changes
they perceived in teaching practices after participating in the training workshops and
strategies implemented to maintain the achieved level of English language proficiency by
EFL teachers at upper secondary schools in the Central Highland of Vietnam were also
investigated. The study employed a mixed-methods approach with a concurrent research
design and content-based data analysis. One hundred and fifty EFL teachers, having
participated in the ELP training workshop(s) and achieved the CEFR-C1 level as
professional standards by authorized universities, participated in the study. The data
collection was based on the questionnaire, reflective report and interview. The analysis of
the three different data sources and the triangulation of the data helped create an advanced
level of emergent contents. Overall, findings have indicated that the more than 90% of the
EFL teachers agreed that their language knowledge and skills were well improved after the
training apart from the quantified evaluation-the CEFR-C1 level. English language
proficiency training workshops were believed to be necessary and important for teachers’
language proficiency improvement and maintenance. After the training, the EFL teachers
perceived changes in teaching practices, and they were aware of the importance of
maintaining the achieved level of proficiency. While many EFL teachers acknowledged
struggles to improve and maintain the achieved level of proficiency, they made efforts to
handle difficulties and challenges to implement different strategies to maintain the achieved
level of proficiency. There were six strategies identified as the most commonly implemented
by the teachers for their language proficiency maintenance. On the basis of the findings,
practical implications have been made to increase the sustainability of professional
development for upper secondary school EFL teachers in the Central Highland. The study
has proposed a blueprint for future policies on language proficiency training and post-
training activities in the Central Highland of Vietnam, and other areas with the same context
can perhaps benefit from.