The purpose of this supplement is to facilitate researchers’ and clinicians’ use of the Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS). The NNNS was developed for the National Institutes of Health (NIH) to assess the neurobehavior of drug-exposed and high-risk infants. In the early 1990s, the NIH began the multisite (Detroit, Michigan; Memphis, Tennessee; Miami, Florida; and Providence, Rhode Island) Maternal Lifestyle Study (MLS), a prospective longitudinal study of in utero cocaine exposure, under the auspices of the National Institute of Child Health and Human Development Neonatal Research Network. The NNNS was developed for use in the MLS under a separate “Neurobehavioral Contract” from the National Institute on Drug Abuse to provide measures for the MLS that were sensitive to drug effects. Part of the mission of the contract was also the dissemination of the measures, a mission fulfilled, in part, by this supplement. The material provided here will enable readers to determine their interest in using the exam. Procedures for learning the exam are described in this issue, and a training manual and assessment kit will be published by Brookes Publishing.This issue includes a preface by T. Berry Brazelton, MD, followed by a history and description of the NNNS and the NNNS procedures, which shows how to perform and score the exam. This is followed by two articles providing NNNS data from the MLS and a low-risk term sample. We then provide an article on clinical uses of the NNNS. Appendices are also included with information on how to compute summary scores.The NNNS represents the combined knowledge of many scientist-clinicians as well as examiners with extensive experience in the neurobehavioral assessment of normal and at-risk infants.We thank the National Institutes of Health for permission to disseminate this material, with special thanks to Linda Wright, National Institute of Child Health and Human Development project officer, and Vincent Smeriglio, National Institute on Drug Abuse project officer, whose combined vision helped lead to the development of this exam. We also thank the Johnson & Johnson Pediatric Institute for generous financial support of this supplement. This work was supported by National Institute of Child Health and Human Development grant 1U10-HD279004 and contract NO1-HD-2-3159, jointly supported by National Institute on Drug Abuse and National Institute of Child Health and Human Development.We thank our mentor, T. Berry Brazelton, for insight, guidance, and support. Other individuals who contributed to the development of the NNNS include Kevin Nugent, Zackariah Boukydis, and Rosemarie Bigsby. From the Maternal Lifestyle Study, we acknowledge the contribution of the other principal investigators, Charles Bauer, Seetha Shankaran, and Henrietta Bada, and the examiners in the 4 sites who provided valuable feedback during the pilot testing and training phase with the NNNS, including Andrea Nadra, Rebecca Van Vorst, Laura Dietz, Lisa Eisen, Susan Gauthier, Kim Yolton, and Eunice Woldt. Kim Yolton was involved from the beginning and has provided new input along with Melissa Fallone and Lynne Andriozzi. Special thanks go to Linda LaGasse for scientific as well as editorial input. Elizabeth Rahdert from the National Institute on Drug Abuse helped start this project. We also thank Dan Griffith.