The 27th meeting in the International Neurotoxicology Conference Series (NEUROTOX 27) will address the theme of Environmentally Triggered Neurodevelopmental Disorders: Focus on Endocrine Disruption and Sex Differences in Autism, ADHD, and Schizophrenia. NEUROTOX 27 will convene October 30 to November 2, 2011 at the Sheraton Imperial Hotel and Conference Center in Research Triangle Park, NC. Each conference in the series is devoted to a timely, forward-thinking theme that has significant impact on environmental health and neurological disorders, and there exists enough evidence that the science on the theme will be advanced by being scrutinized in this established, multidisciplinary, focused, program approach. To be at the forefront of science the conference chair partners with internationally-recognized scientific experts on the focused theme to co-organize the meeting and identify the session themes, topics and speakers. This year the meeting will be highly focused on two endpoints: 1) endocrine disruption and 2) sex differences, in three complex neurodevelopmental disorders which have factors in common: 1) autism, 2) ADHD and 3) schizophrenia. The plenary sessions have been structured to present the latest clinical and basic research in a format that will facilitate discussion, address specific questions (published in the Program) and be conducive to a cross-cutting discussion on common factors on the last day of the conference after evidence has been presented. Significance: Clinical disorders of the central nervous system arise from complex interactions among multiple risk factors. Genetic mutations, polymorphisms, and copy number variations confer heritable susceptibility to environmental stressors including exposures to xenobiotic chemicals, shifts in nutritional status, and medical interventions. The prevalence of autism has increased dramatically and there is emerging evidence that suggests increases in the diagnosis of ADHD and schizophrenia. Although some of these trends can be explained by increased awareness, diagnostic drift and changes in diagnostic criteria, environmental factors are likely contributors. An increasing number of persistent organic pollutants (POPs) and metals have been shown to alter endocrine signaling mediated by thyroid, estrogen and androgen hormones. Many of these chemicals are detected in maternal and gestational tissues, breast milk, and neonates at levels of concern. The consequences of endocrine disruption during critical periods of neurodevelopment have far-reaching implications. NEUROTOX 27 will present the latest evidence and controversies linking endocrine disruption and neurodevelopmental disorders, with a focus on autism, ADHD, and schizophrenia. These 3 disorders share several clinical features including strong gender bias, immune impairments, and an association with seizure disorders. Yet these disorders differ in onset of clinical symptoms that may provide clues to critical windows of susceptibility to specific endocrine disruptors and their underlying mechanisms. The conference is designed to present attendees with the latest state-of-the-science about the role of the endocrine system in environmentally triggered disorders and stimulate vigorous discussion among experts from different backgrounds to help advance the science related to the theme. Public Health Relevance: The public health relatedness of this application is that the results of this conference will help us better understand the role of the environment, endocrine disruption, and sex differences in autism, ADHD and schizophrenia. NEUROTOXICOLOGY 27 will convene internationally recognized experts to present the latest evidence and controversies linking endocrine disruption and environmentally triggered neurodevelopmental disorders, with a focus on autism, ADHD, and schizophrenia. The public health impact of these disorders is enormous. Today, one in 110 children (and one in 70 boys) born in the U.S. is diagnosed with autism, and the numbers have been rising 10% to 17% a year. Autism has a range of features that suggest the possibility of endocrine-related alterations, including a much higher prevalence in males. Other clinical clues invite critical investigation of potential toxicological, immune and endocrine disruptive contributors to autism, ADHD and schizophrenia. Peer-reviewed papers from NEUROTOXICOLOGY 27 will be published rapidly, disseminated internationally, and made accessible online to readily reach target audiences.