A strong command of vocabulary is to some extent attributed to a competent learner of
English. This research investigated the application of the morphological method, intended
for sophomores majoring in English at the School of Foreign Languages (SFL) – Thai
Nguyen University (TNU). This paper aims at analyzing several problems that students
experience during the process of acquiring new words by roots & affixes and assessing the
influence of this method on developing the lexical knowledge of students. To this end, the
experimental method was employed in treating the data. Based on the data collection
instruments, including questionnaires, pre- and post-test, and the assumptions of the
author, a baseline for evaluating the lexical capacity and the effectiveness of morphemic
strategy training for 44 second-year students at SFL was established. Along with this, a
comparative methodology was used, specifically: finding the effects by comparing contrast
and experimental group. After combining the data collected from questionnaires and tests,
it can be seen that using morphemic method has a significant effect on lexical knowledge
acquisition for students.