The study investigated influence of personality and social factors on delinquent behaviour among secondary school adolescents in Obio/Akpor LGA of Rivers State. The design for the study was expost-facto. The sample for the study was 300 students. Two instruments were used to collect data for the study and they were Adolescent delinquent Behaviour and Neo-Personality inventory with reliability of 0.77 and 0.82 respectively. Five research questions as well as five hypotheses were answered and tested for in the study. Responses for answering research question 1 were analysed with multiple regression, those for research question 2 with beta values associated with multiple regression. Research question 3 and 4 were answered with mean and standard deviation. Hypotheses 1 was tested with ANOVA... associated with multiple regression, hypotheses 2 was tested with multiple regression while hypotheses 3 and 4 were tested with independent t-test. The study found that, extraversion and openness to experience jointly had about 5.4% influence on the variations on the development of delinquent behaviour, Furthermore, adolescents whose peer group is clique had a higher mean scores on the development of delinquency than those whose peer group is isolates. Based on the findings; it was recommended that, educational programmes should be organized which will help young people learn how to engage in positive self-appraisal, deal with conflict and control aggression. Contributions to knowledge were made.