This action research was conducted to help students develop their vocabulary skills through parent-teacher collaboration and to help parents and teachers understand that collaboration is an important aspect that warrants enough attention. Thus, few studies have focused on parent-teacher collaboration to help students develop their vocabulary skills. This study applies Beck, McKeown, and Kucan’s (2013) three-tiered model of vocabulary to gauge the vocabulary level of the students. Moreover, the researchers used quasiexperimental research to test whether or not collaboration between teachers and parents is effective in improving the vocabulary skills of students. This study used pre-test and post-test to measure students’ vocabulary skills. A training matrix was developed by the researchers to be used for the monthlong duration of the experiment. In the matrix, the researchers employed vocabulary exercises during the experiment. The data gathered were statistically analyzed using SPSS. The results of the study are presented and discussed with reference to the aim of the study; (1) based on the computed mean of the pre- and post-tests, it was found out that there is an increase in the students’ level of performance in vocabulary. Moreover, (2) the results accepted the hypothesis that there is a significant difference before and after the exposure to parent-teacher collaboration. Lastly, (3) it is proposed that parent-teacher partnership shall be the next priority of the school Continuous Improvement Program (CIP) which will highlight communication skills primarily.