Low proficiency ESL learners often encounter a lot of learning problems, particularly due to their lack of vocabulary, which is evident in their incorrect usage of words. This study was an attempt to aid 85 low proficiency ESL learners to easily comprehend the forms and functions of 80 target words, selected from the 2000 level General Word List, using the syntactic tree structure approach. Prior to the intervention, a vocabulary test based on 80 words, which were later introduced to the students in their course book, was administered to the students. The same test was given again to the students upon the completion of the third lesson. To determine the possible significant influence of the intervention, the pre-test and post-test data were analysed using the paired-samples t-test. The analysis yielded a significant result (t (84) = 7.31, p < .05 (two-tailed)). When the students’ mean test scores of the two tests were compared, a statistically significant increase of 7.5 points was observed, implying the success of the intervention. The calculated effect size was also large (ŋ=.39). However, since no control group was introduced in the study, caution should be taken in making any strong claims on a causal relationship.