This research sought to determine the level of productive vocabulary knowledge of the students grouped according to type of school and curriculum year level; performance of the students in the vocabulary test categorized according to frequency levels; their breadth of productive vocabulary knowledge related to type of school enrolled in, curriculum year level, and exposure to information media; and the intervention strategies that may be proposed to enhance students' productive vocabulary knowledge. The Vocabulary Level Test (VLT) designed by Nation (1990) and widely used as a second language diagnostic test in New Zealand and other English-speaking countries, was adopted and used as a tool to measure selected pre-service teachers' breadth or size of productive vocabulary knowledge against word-frequency lists. The subjects were the pre-service teachers enrolled in state and private colleges. Only the freshmen and seniors taking up Bachelor in Elementary Education and Bachelor in Secondary Education were chosen to participate in the study. Results of the investigation suggest that: (1) Pre-service teachers in both public and private schools still lack the productive vocabulary knowledge in English to make them proficient and effective speakers and writers; (2) Students from state colleges have wider vocabulary knowledge than those from the private colleges. However, the breadth of their vocabulary knowledge is not sufficient to make them effective user of the language; (3) Longer exposure to the English language in the school helps increase vocabulary size; and (4) Exposure to information media helps widens breadth of productive vocabulary. It was recommended that: (1) Productive Vocabulary Levels Test by Nation (1990) should be used, then, in all tertiary institutions as an additional quantitative measure for students' vocabulary size; (2) Students should be provided adequate access to the computer/internet, cable network, English reading materials, and television in the school; and (3) Teaching time allotted for vocabulary development in all classes where English is used as the medium of instruction should be lengthened.