This study examined Thai senior high school EFL learners' receptive and productive knowledge of English polysemous phrasal verbs. The research employed the framework developed by Garnier and Schmitt (2015), which is the most widely acknowledged and functional concept of English polysemous phrasal verb knowledge. A battery of tests measuring the participants' receptive and productive knowledge of English polysemous phrasal verbs and vocabulary size were administered. The results indicated that Thai EFL high school learners had an intermediate understanding of polysemous English phrasal verbs. On the receptive knowledge test, participants scored higher than on the controlled and uncontrolled productive knowledge assessments. In addition, the results demonstrated a positive correlation between vocabulary size and receptive / productive knowledge of English polysemous phrasal verbs. The correlation analysis also revealed that a number of English polysemous phrasal verb knowledge dimensions were interrelated. This study provides empirical evidence that Thai EFL learners' knowledge of English polysemous phrasal verbs develops along a continuum from receptive to productive use. This research also suggests that polysemous phrasal verbs are multidimensional and progressive. Longitudinal experiments with varying L1 and education levels would be beneficial for future research.