<p>Despite the numerous benefits associated with leisure time physical activity (LTPA), it is quite worrisome that the habit of regularly engaging in LTPA is rare among Nigerians, especially among adolescents who are found in myriads of sedentary lifestyle behaviour as a result of technological and economical advancement. The present study examined socio-demographic and psychological determinants of LTPA among adolescents in Nigeria. A cross-sectional study was conducted and multistage sampling technique was employed to recruit 1200 adolescents (Male =59.7%; Female =40.3%; Age: 10-19years) from twelve secondary schools in Southwest States, Nigeria. Physical Activity Self-Efficacy for Adolescent (PASE), The Physical Activity and Leisure Motivation Scale (PALMS), Activity Questionnaire for Adults and Adolescents (AQuAA) and Self-developed Socio-demographic Questionnaire were used to collect the data. Data were analyzed using statistics of frequency count, percentages & Multiple Regression. The result of the study showed that socio-demographic (F(8,1191) = 4.980; p< .05; R2 = .28) accounting for 28% of its variance and psychological factors (F (2,1197) =31014.342, p< .05; R2 = .99) accounting for 99% of its variance) were significant. Based on the findings, adolescents in Southwest states in Nigeria do not meet the World Health Organization recommendations on physical activity. Both socio-demographic and psychological factors significantly determined LTPA and these factors could be taken into account in the development of interventions to increase LTPA levels throughout the life course among adolescents in Nigeria. </p><p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/edu_01/0852/a.php" alt="Hit counter" /></p>