The Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands (Hoogman, Guimaraes, Shumskaya, Wolfers, Bralten, Franke); the Donders Institute for Brain, Cognition, and Behavior, Radboud University, Nijmegen, the Netherlands (Hoogman, Shumskaya, Mennes, Wolfers, Buitelaar, Bralten, Franke); the Department of Child and Adolescent Psychiatry, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands (Muetzel, El Marroun, White, Tiemeier); the Department of Epidemiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands (Muetzel); the Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition, and Behavior, Nijmegen, the Netherlands (Guimaraes, Zwiers, Buitelaar); the Imaging Genetics Center, Stevens Neuroimaging and Informatics Institute, Keck School of Medicine of USC, Marina del Rey, Calif. (Jahanshad, Thompson); National Human Genome Research Institute, Bethesda, Md. (Sudre, Shaw); the Department of Behavioral Neuroscience, Oregon Health and Science University, Portland (Earl, Fair, Nigg); the Department of Psychiatry and Forensic Medicine, Autonomous University of Barcelona, Cerdanyola del Vallès, Spain (Soliva Vila, Ramos-Quiroga, Vilarroya); Instituto ITACA, Polytechnic University of Valencia, Valencia, Spain (Vives-Gilabert); the Olin Neuropsychiatry Research Center, Hartford Hospital, Hartford, Conn. (Khadka, Novotny, Stevens); University of Groningen, University Medical Center Groningen (UMCG), Department of Psychiatry, Interdisciplinary Center Psychopathology and Emotion Regulation (ICPE), Groningen, the Netherlands (Hartman, Schweren); Faculty of Behavioral and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam (Heslenfeld); the Department of Child and Adolescent Psychiatry, University of Groningen, University Medical Center Groningen, the Netherlands (Hoekstra); NICHE Lab, Department of Psychiatry, UMC Utrecht Brain Center, Utrecht, the Netherlands (Ambrosino, Oranje, de Zeeuw, Durston); Laboratory of Psychiatric Neuroimaging (LIM-21), Department and Institute of Psychiatry, Faculty of Medicine, University of São Paulo, São Paulo, Brazil (Chaim-Avancini, Rosa, Zanetti, Busatto); the Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), University of São Paulo, São Paulo, Brazil (Chaim-Avancini, Rosa, Zanetti, Busatto); the Developmental Imaging Group, Murdoch Children's Research Institute, Melbourne, Australia (Malpas); the Clinical Outcomes Research Unit (CORe), Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Australia (Malpas); the Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia (Malpas); the Child Neuropsychology Section, University Hospital RWTH Aachen, Aachen, Germany (Kohls, Konrad; Child and Adolescent Psychiatry, University Hospital RWTH Aachen, Aachen, Germany (Polier, Seitz); Institute of Neuroscience and Medicine–Brain and Behavior (INM-7), Research Center Jülich, Jülich, Germany (Polier); the Clinical and Research Programs in Pediatric Psychopharmacology and Adult ADHD, Department of Psychiatry, Massachusetts General Hospital, Boston (Biederman); the Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston (Biederman, Doyle); the Center for Genomic Medicine, Massachusetts General Hospital, Harvard Medical School, Boston (Doyle); the Departments of Neurosciences, Radiology, and Psychiatry and the Center for Multimodal Imaging and Genetics, University of California San Diego (Dale); the Clinical and Translational Neuroscience Laboratory, Department of Psychiatry and Human Behavior, University of California Irvine, Irvine (van Erp); the Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children’s Hospital Medical Center, and the Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati (Epstein, Tamm); the Center for Human Development, University of California San Diego, San Diego (Jernigan); the Division of Molecular Psychiatry, Center of Mental Health, University of Würzburg, Würzburg, Germany (Ziegler, Lesch); the Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, Amsterdam (Schrantee, Reneman); the Department of Clinical Medicine, University of Bergen, Bergen, Norway (Høvik); the Division of Psychiatry, Haukeland University Hospital, Bergen, Norway (Høvik, Haavik); the Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway (Lundervold); the K.G. Jebsen Center for Neuropsychiatric Disorders, Department of Biomedicine, University of Bergen, Bergen, Norway (Lundervold, Haavik); the School of Psychology and the Department of Psychiatry, School of Medicine, and the Trinity College Institute of Neuroscience, Trinity College Dublin, Ireland (Kelly); the Department of Child and Adolescent Psychiatry, NYU Langone Medical Center, New York (Kelly, Castellanos, Yoncheva); the Department of Psychiatry, Trinity College Dublin, Ireland (McCarthy, Skokauskas, Frodl); the Centre for Advanced Medical Imaging, St. James's Hospital, Dublin, Ireland (McCarthy); the Center for Child and Adolescent Mental Health, NTNU, Norway, Norwegian University of Science and Technology, Norway (Skokauskas); the Center for MR Research, University Children's Hospital, and the Zurich Center for Integrative Human Physiology, Zurich (O’Gorman Tuura); Magnetic Resonance Image Core Facility, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain (Calvo, Lazaro); the Department of Child and Adolescent Psychiatry and Psychology, Institute of Neurosciences, Hospital Clinic, Barcelona, Spain (Lera-Miguel, Nicolau, Lazaro); the Department of Child and Adolescent Psychiatry, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London (Chantiluke, Christakou, Cubillo, Rubia); the School of Psychology and Clinical Language Sciences, Centre for Integrative Neuroscience and Neurodynamics, University of Reading, Reading, U.K. (Christakou); the Department of Paediatrics, University of Melbourne, Australia (Vance, Coghill, Silk); the Department of Neuroscience, Brighton and Sussex Medical School, Falmer, Brighton, U.K. (Cercignani, Gabel, Harrison); the Social, Genetic, and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London (Asherson, Kuntsi); the Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Mannheim, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany (Baumeister, Brandeis, Hohmann, Banaschewski); the Department of Child and Adolescent Psychiatry and Psychotherapy, Psychiatric Hospital, University of Zurich, Zurich (Brandeis, Brem, Walitza); the Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich (Brandeis, Brem, Walitza); the D’Or Institute for Research and Education, Rio de Janeiro (Bramati, Tovar-Moll, Mattos); the Morphological Sciences Program, Federal University of Rio de Janeiro, Rio de Janeiro (Tovar-Moll); the Department of Psychiatry and Psychotherapy, University Hospital of Tübingen, Tübingen, Germany (Fallgatter, Schwarz, Ethofer); LEAD Graduate School, University of Tübingen, Germany (Fallgatter); the Department of Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany (Kardatzki, Ethofer); the National Medical Research Center for Children's Health, Department of Magnetic Resonance Imaging and Densitometry, Moscow (Anikin); the National Medical Research Center for Children's Health, Moscow (Baranov, Solovieva); Russian National Research Medical University, Ministry of Health and Social Development of the Russian Federation, Central Clinical Hospital MSHE, Moscow (Namazova-Baranova); the National Medical Research Center for Children's Health, Laboratory of Neurology and Cognitive Health, Moscow (Gogberashvili, Karkashadze); the National Medical Research Center for Children's Health, Department of Information Technologies, Moscow (Kapilushniy); the Department of Pediatrics, Erasmus MC–Sophia, Rotterdam, the Netherlands (El Marroun); the Department of Psychology, Education, and Child Studies, Erasmus University Rotterdam, Rotterdam, the Netherlands (El Marroun); the Department of Radiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands (White); Federal University of Rio de Janeiro, Rio de Janeiro (Mattos); the Department of Psychiatry, University of Melbourne, Melbourne, Australia (Coghill); the Murdoch Children's Research Institute, Melbourne, Australia (Coghill, Silk); the Division of Neuroscience, University of Dundee, Dundee, U.K. (Coghill); the Child and Adolescent Mental Health Center, Capital Region Copenhagen (Plessen); the Division of Child and Adolescent Psychiatry, Department of Psychiatry, University Hospital Lausanne, Switzerland (Plessen); the Department of Neuroimaging, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London (Mehta, Paloyelis); Sussex Partnership NHS Foundation Trust, Swandean, East Sussex, U.K. (Harrison); the Monash Institute for Cognitive and Clinical Neurosciences (MICCN) and the School of Psychological Sciences, Monash University, Melbourne, Australia (Bellgrove); Deakin University, School of Psychology, Geelong, Australia (Silk); the Department of Medicine, University of Barcelona, Barcelona, Spain (Lazaro); the Department of Psychiatry and Psychotherapy, Otto von Guericke University Magdeburg, Germany (Frodl); the German Center for Neurodegenerative Diseases (DZNE), Germany (Frodl); Bezirksklinikum Regensburg, Germany (Zentis); the Nathan Kline Institute for Psychiatric Research, Orangeburg, N.Y. (Castellanos); the Brain Imaging Center, Amsterdam University Medical Centers, Amsterdam (Reneman); the Department of Child and Adolescent Psychiatry, Psychosomatics, and Psychotherapy, Tübingen, Germany (Conzelmann); the Department of Psychology, Biological Psychology, Clinical Psychology, and Psychotherapy, University of Würzburg, Würzburg, Germany (Conzelmann, Pauli, Baur-Streubel, Zierhut); the Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine, I.M. Sechenov First Moscow State Medical University, Moscow (Lesch); the Department of Neuroscience, School for Mental Health and Neuroscience (MHeNS), Maastricht University, Maastricht, the Netherlands (Lesch); the Department of Psychiatry, Psychosomatic Medicine, and Psychotherapy, University Hospital Frankfurt, Frankfurt, Germany (Reif); JARA Institute Molecular Neuroscience and Neuroimaging (INM-11), Institute for Neuroscience and Medicine, Research Center Jülich, Germany (Konrad); Translational Neuroscience, Child and Adolescent Psychiatry, University Hospital RWTH Aachen, Aachen, Germany (Oberwelland Weiss); Cognitive Neuroscience (INM-3), Institute for Neuroscience and Medicine, Research Center Jülich, Germany (Oberwelland Weiss); the Department of Psychiatry, Faculty of Medicine, University of São Paulo, São Paulo, Brazil (Busatto, Louza); the Clinical Neuropsychology Section, Vrije Universiteit Amsterdam, Amsterdam (Oosterlaan); Emma Children’s Hospital Amsterdam Medical Center, Amsterdam (Oosterlaan); the Department of Pediatrics, VU Medical Center, Amsterdam (Oosterlaan); the Department of Psychiatry, Yale University School of Medicine, New Haven, Conn. (Stevens); the Department of Psychiatry, Vall d’Hebron University Hospital, Barcelona, Spain (Ramos-Quiroga); Biomedical Network Research Center on Mental Health (CIBERSAM), Barcelona, Spain (Lazaro, Ramos-Quiroga); Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain (Vilarroya); the Department of Psychiatry, Oregon Health and Science University, Portland (Fair, Nigg); Karakter Child and Adolescent Psychiatry University Center, Nijmegen, the Netherlands (Buitelaar); Departments of Psychiatry and of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, New York (Faraone); NIHM, Bethesda, Md. (Shaw); the Department of Social and Behavioral Science, Harvard T.H. Chan School of Public Health, Boston (Tiemeier).