In the area of second and foreign language studies, researchers have revealed how extensive repertoire of vocabulary is capable of expanding learners’ language competence or mastery. Various computer-based tools have been proposed to improve vocabulary learning among English language learners. One of them is the use of Twitter, an online micro blogging network that allows users to send and read text-based messages of up to 140 characters, which is termed as “tweets”. Due to such limitation, previous studies have noted how users tend to use shorter forms of a word or invent their own words in their tweets. Such activities are seen as a threat to vocabulary learning. This paper reports a case study on the use of Twitter in vocabulary learning among first-year university students with low proficiency in English. A total of 38 students were selected and a pre-test was conducted to distinguish their vocabulary level. They received two tweets on vocabulary from the instructor on a daily basis for ten weeks and were told to learn the words through several activities using tweets. At the end of the tenth week, a post-test was carried out. The findings revealed minimal but significant improvements in the students’ vocabulary level. Although the scores from the tests did not show a great increase, the students were able to construct sentences using the vocabulary learned mostly via tweets. This paper also proposes several methodological considerations on the use of Twitter for vocabulary learning particularly as a way to raise awareness.