INTRODUCTION: This study aims to assess the economic impact of delays and inadequate diagnosis and treatment for neurodevelopmental disorders (NDDs) in France, affecting 2 to 3 million individuals. Neurodevelopmental disorders, including autism spectrum disorder (ASD), learning disabilities, and attention deficit hyperactivity disorder (ADHD), are often described as "invisible" disabilities, but they generate significant societal costs. METHOD: The study was conducted with the support of Ashoka France as part of a collaboration between Goodwill-Management and the Aloïs Association. Goodwill-Management, a firm specializing in support for social economy organizations, offers pro bono assistance each year for social impact assessment. In 2022, it selected the project of the Aloïs Association, a center of expertise on cognitive disorders at all stages of life, based in Paris, to conduct the first medico-economic study on NDDs in France. The methodological approach comprised a thorough literature review, data collection from public organizations, and detailed economic analysis. The study sought to identify the potential cost-saving levers and highlight the economic burden of late diagnosis and variable care pathways for NDDs. RESULTS: The study revealed that the economic cost of NDDs in France is estimated at approximately 28 billion euros per year. In comparison, the estimated costs are 74 billion dollars in the United States and 37 billion dollars in Canada. A major contributor to these costs is the delay in diagnosis, coupled with the heterogeneity of care, which significantly impacts the professional lives of individuals with NDDs and their caregivers. CONCLUSION: The findings underscore the importance of early diagnosis and standardized care pathways to reduce societal costs and improve the quality of life for affected individuals. To reduce societal costs and improve the quality of life for those affected, the proposed recommendations emphasize the importance of early diagnosis, increasing access to care methods recommended by the HAS (French National Health Authority), and promoting targeted prevention and psychoeducation interventions within companies, aimed at supporting employees suffering from these disorders as well as employee caregivers. Implementing these measures is expected to generate substantial economic savings and support the inclusion and well-being of individuals with neurodevelopmental conditions.