This study examined the use of Twitter for vocabulary learning among 38 low proficiency students over 10 weeks. Students received two tweets with vocabulary words per day from the instructor and engaged with the words on Twitter. Pre- and post-tests showed minimal but across-the-board improvements in students' vocabulary levels. While Twitter allows for rapid sharing of concise vocabulary and access to a large corpus of words, it also lacks control over learning and privacy. The study found potentials for vocabulary growth through Twitter but recommends guidelines for its effective educational use.