Children with Neurodevelopmental Disorders (ND) often show co-occurring challenges with their ability to regulate their emotion and behavior, as evidenced by high rates of externalizing behavioral challenges. This chapter provides an overview of evidence-based parent-mediated interventions to lessen externalizing behaviors in ND children. We describe the rationale for, and key components of, parent-mediated interventions, such as behavioral parent training (BPT) and describe the research support for several widely used interventions. Our review of the research showed that the components of these interventions that have been found to be effective in improving child outcomes are psychoeducation, stress management, relational enhancement, behavior management, and parent-mediated skills acquisition. We subsequently describe parent (e.g., motivation, attributions, culture, mental health) and child (e.g., severity of externalizing behaviors, callous-unemotional traits) factors that influence intervention outcomes and conclude with a discussion of ways to potentially improve the effectiveness of interventions.