Recent studies indicate that adolescents often experience musculoskeletal pains in two or more body locations. However, previous studies have mainly focused on localized pains, and the determinants of multiple musculoskeletal pains in adolescents are not well known. The present study was set to evaluate the role of psychosocial, mechanical, and metabolic factors in adolescents' musculoskeletal pains in multiple locations. The study population consisted of the 1986 Northern Finland Birth Cohort; 15- to 16-year-old adolescents (n=6986), who responded to a mailed questionnaire in 2001. We assessed the associations of emotional and behavioral problems, physical activity, sitting time, sleeping time, overweight and smoking with musculoskeletal pains using multinomial logistic regression. Multiple pains were common, 23% of boys and 40% of girls reported feeling pain in at least three locations over the past 6 months. These pains were not only associated with anxious/depressed symptoms, withdrawn/depressed symptoms, somatic complaints, rule-breaking and aggressive behavior, social problems, thought and attention problems, but also with high physical activity level, long sitting time, short sleeping time and smoking, among both boys and girls. In addition, pain in three to four locations associated with overweight in girls. A high number of psychosocial, mechanical and metabolic factors associated strongly with multiple pains. In conclusion, multiple musculoskeletal pains were strongly associated with psychosocial complaints, but also with mechanical and metabolic factors. Reported musculoskeletal pains in multiple locations in adolescence may have both peripheral (trauma, decreased regenerative ability) and central (sensitivity) causes.