Individual variability of second language learners is considered one of the most important factors in the second language acquisition. This paper discusses the PhD level research conducted in the area in various universities. In all, the different personality variables like empathy, self- esteem, anxiety and extroversion/ introversion are defined first. This is followed by a discussion on five theses that deal with the different aspects of relationships between a second language learner’s personality and his/ her proficiency in the second language. A summary of the work done by the researcher, the methodologies used, conclusions reached, is given.