Objective: Type 1 diabetes (T1DM) is a chronic life-threatening disease that requires strict adherence to daily treatment tasks. Although necessary for survival, children who present with behavior problems tend to show problems complying with the treatment regimen, thereby increasing their risk for morbidity and premature mortality. The risk of poor treatment adherence is hypothesized to be lower for these children, however, if they engage in more routine behaviors. Given the potential clinical implications, this hypothesis and two theoretical models proposed to elucidate the underlying psychological process for the role of child routines in treatment adherence were evaluated empirically. The first model hypothesized that child routines protect (moderator variable) behaviorally problematic children from poor treatment adherence, whereas the alternative model hypothesized that child routines mediate the relation between childhood behavior problems and poor treatment adherence. Methods: Parents of T1DM patients (N = 111) ranging from 6 to 16 years of age (M = 12 years) reported on their child's behavior problems, routine behaviors, and adherence to treatment for T1DM using standardized measures. Baron and Kenny's statistical procedures for testing moderation and mediation hypotheses were used to evaluate the proposed models. Results: Regression analyses did not support the moderation hypothesis but did support the hypothesis that engaging in child routines mediates the relation between childhood behavior problems and poor treatment adherence. Conclusions: Parents of behaviorally problematic children diagnosed with T1DM might be advised to instill routines in their child's daily activities to increase the likelihood of treatment adherence, and thereby reduce the risk of morbidity and early mortality. Implications for clinical interventions are discussed. © The Author 2006. Published by Oxford University Press on behalf of the Society of Pediatric Psychology. All rights reserved.