The purposes of this study were to develop web-based teaching materials for teaching vocabulary to college students and to measure the effect of them. The developed web-based teaching materials consisted of six steps which were arranged to learn vocabularies effectively. After teaching the target vocabularies to the subjects with the materials for three months, it was clear that the web-based teaching materials developed in this study was effective to foster learners' ability to memorize the spellings of English words and to understand the meanings of the phrases in which the target words were used. We were not certain,however,whether the teaching materials could foster learners' ability to acquire the meanings of individual English words.