Neurodevelopmental disorders (NDDs) emerge early in life and are associated with functional impairment for children and their families. Amongst children with NDDs, sleep problems are highly prevalent and can have widespread negative effects on children's health, functioning, and quality of life. However, there are few established evidence-based sleep interventions and access to these is limited. This three-study dissertation aimed to lay the groundwork for developing a transdiagnostic eHealth parent-implemented intervention for children with four NDDs (Autism Spectrum Disorder [ASD], Attention-Deficit / Hyperactivity Disorder [ADHD], Cerebral Palsy [CP], and Fetal Alcohol Spectrum Disorder [FASD]). Study 1 is a systematic review of online parent-implemented interventions for NDD symptoms and other behaviour problems in children with NDDs. Twelve interventions were identified, for ASD (n = 8), ADHD (n = 3), and FASD (n = 1). Despite promising evidence for the effectiveness of online parent-implemented interventions and their potential to resolve treatment access problems, no interventions currently qualify as evidence-based and more large-scale trials are required. Study 2 qualitatively explored barriers and facilitators to sleep treatment access, implementation and provision experienced by parents and health care professionals (HCPs) of children with ASD, ADHD, CP and FASD via focus groups / interviews. Similar themes emerged across all NDDs. Key barriers reported by parents (n = 43) and HCPs (n = 44) included lack of knowledge / awareness of sleep problems and their treatment in NDDs, limited access to treatment, the demanding nature of treatments, and parent factors (e.g., exhaustion). Key facilitators included education, support, behavioural treatment approaches, and the ability to modify treatments to account for NDD symptoms. In Study 3, parents of children with ASD, ADHD, CP, or FASD (n = 20) implemented an eHealth parent-implemented insomnia intervention designed for typically developing children, and evaluated the intervention's usability, accessibility, and feasibility. Parents found it usable, acceptable, and feasible, and suggested modifications to make the intervention more useful for children with NDDs. Overall, these studies demonstrate the need for an accessible sleep intervention, and support a transdiagnostic approach to treating sleep problems in children with NDDs.