The idea that the newborn is an uncharted and therefore pliable organism, which can be formed according to the will of its parents, has long been rejected, especially after the existence of rules of behavior not only in full-term but also in marginally premature newborns, which are affected by various both prenatal and perinatal factors. The ability of newborns to determine the rules of their behavior according to the stimuli they receive from internal and external factors, has been the subject of many years of research and has led pediatricians and other health professionals to develop a model for grading these newborn abilities. Thus, the Neonatal Behavioral Assessment Scale (NBAS) was created, and it has been used by researchers for more than 40 years. It is a research tool with wide application, as many of the points it addresses, can be integrated into other means of assessing the newborn’s abilities. This scale also has an ever-evolving application as a clinical tool in parental assessment.