Oral communication is a critical factor for effective teaching (Prozesky, 2010). The success of facilitating learning lies mainly on how good teachers are in communicating learning outcomes, criteria, and implementing lesson plans. In the current educational reform in the Philippines, an English proficiency test is administered for all teachers to inform professional development programs. The test does not include assessing the oral communication proficiency of teachers due to unavailability of a tool that can be used. However, this focus area has been emphasised by several reports to be included because there are many teachers whose oral communication skills are problematic, making their teaching less effective. Thus, it is necessary to assess these skills to ensure effective delivery of learning and teaching activities. This problem is compounded with the use of English language as an additional language for teaching as it adds another layer of difficulty for effective use of the language (Low, 2014). To address these issues, this study attempts to develop a teacher oral communication proficiency tool framed as rubrics focused on how teachers communicate inside the classroom whilst teaching. I established the indicators of the construct and the performance criteria following the work of Griffin (2018) through literature review and data from focus groups with seven lead teachers. A 6-point Likert scale was used and the tool and subjected it for a series of validation and pilot testing. In the main study, I recruited primary and secondary teachers and 584 completed the survey. The data were randomly assigned into two subsets, one for exploratory factor analysis and the other one for confirmatory factor analysis using Mplus software (Muthen & Muthen, 2012) to explore the domains of the construct. I will report the results of our study including the dimensionality of the construct and the developmental progression of the various oral proficiency skills. Also, I will discuss the implications of the dimensionality of the construct on expanding our understanding and defining the oral communication skills needed by teachers. The presentation will conclude on how the results of assessing teacher oral communication proficiency using the tool can be used to shape teacher professional practice and to inform professional development programs adhering to the principles of Vygotsky’s zone of proximal development.