Current interdisciplinary pain management treatment relieves pain and restores function for many children and adolescents with persistent pain; however, for some, treatment is not successful, and the pain and dysfunction remain. Pain has an ecological context: as children and adolescents engage in their daily lives, receiving sensation through multiple sensory modalities, the perception of uncertain threat can evoke pain and protective responses. Children with disordered patterns of sensory modulation (i.e., those who do not effectively filter irrelevant sensory stimuli, or appropriately adjust arousal to organise a response graded to sensory input) have been shown to report higher pain intensity and duration, lower engagement in daily activities, and are vulnerable to developing insecure attachment. Sensory modulation may contribute to higher pain intensity and reduced function for children and adolescents with persistent pain, and limit the effectiveness of treatment; however, sensory modulation has not yet been investigated in relation to children and adolescents with persistent pain. The purpose of this thesis is to investigate the sensory modulation patterns of children and adolescents with persistent pain. To address the ecological context of pain, the thesis is guided by nonlinear dynamic systems theory (NDST); an ecological framework that serves to explain how neurobiological processes, social relationships, and environmental circumstances interact to influence an individual's response to daily life and potential danger. The aims of the thesis are to consider: (1) the sensory modulation patterns of children and adolescents with persistent pain, (2) whether or not sensory modulation affects their pain and quality of life/capacity to function in daily life, (3) the associations between sensory modulation, attachment insecurity, quality of life/functional ability, and pain, and (4) whether sensory modulation and/or attachment insecurity impact the xi Financial support