The study examined the relationship between neuroticism and social adjustment of undergraduate university students. The study was informed by the Big five personality theory. Concurrent triangulation design was adopted within the mixed method approach. The target population comprised 4805 undergraduate students. The sample comprised 756 students, 1 student counsellor, 1 Caterer and accommodation staff and 1 career guidance making a total sample size of 759. An adapted instrument titled “integrated Questionnaire, Students’ social Adjustment” (IQSA) were used to collect quantitative data from students while Interview schedule was used to obtain qualitative data from student counsellor, caterer and accommodation and career counsellor. The internal validity of the constructs was investigated by subjecting the survey data to suitability tests using the Kaiser-Meyer-Oklin measure of sampling adequacy (KMO Index) and the Bartlett’s Test of Sphericity. Reliability of questionnaires was ensured using internal consistency method and Cronbach’s alpha value was 0.684. There is statistically significant (n=54; r= -.206; p<.05), though negative, relationship between neuroticism personality traits and social adjustment among undergraduate students, with high level of neuroticism personality traits associated to lower social adjustment among the undergraduate students. It was recommended that the university students’ counsellors to assess and identify those students at risk and change their perception on changes experience at the university.