Pediatric persistent pain is associated with poorer physical and psychosocial functioning in children, as well as immediate and long-term societal costs. Onset typically occurs in early adolescence, suggesting that late childhood is a key window for identifying potential intervention targets before pain symptoms become entrenched. This study used population-based data from the Longitudinal Study of Australian Children (n = 3,812) and adopted a biopsychosocial and ecological systems approach to investigate child, family, and sociodemographic factors associated with pain problems in children transitioning to adolescence. The prevalence of at least weekly parent-reported pain in the study sample was approximately 5% at 10 to 11 years of age, and pain continued at 12 to 13 years of age for 40% of these children. Key factors at 10 to 11 years that uniquely predicted parent-reported pain problems at 12 to 13 years were frequency of previous pain (1-3 times weekly: odds ratio [OR] = 7.49; 95% confidence interval [CI], 4.3-13.0; 4-7 times weekly: OR = 17.8; 95% CI, 8.7-36.5) and sleep difficulties (OR = 1.86; 95% CI, 1.16-2.97). This study highlights the importance of early intervention for persistent pain in childhood, because pain complaints in late childhood tend to persist into early adolescence. Perspective: This article used a biopsychosocial and ecological systems approach to understanding predictors of pain problems during the transition to adolescence within a nationally representative community-based cohort. Sleep difficulties at 10 to 11 years uniquely predicted pain at ages 12 to 13 years, suggesting that early intervention using sleep interventions may be a promising direction for future research.