An index of transient mechanical birth trauma (TMBT), consisting of the presence or absence of molding, cephalohematoma, subconjunctival hemorrhage, body bruising, facial bruising, petechiae, forceps marks, diminished arm movements, and sensitivity to sudden position changes, was measured on a convenience sample of 196 healthy newborns. Six dimensions of the Neonatal Behavioral Assessment Scale (NBAS) and other newborn measures also were assessed. Vaginally delivered newborns had more TMBT than those delivered by cesarean section and of newborns delivered vaginally, macrosomics had more TMBT than nonmacrosomics. TMBT positively correlated with range of state, individual reflex items of resistance to left and right arm movement, predominant state during the NBAS exam, and time to complete the NBAS exam. TMBT negatively correlated with newborn state instability and 1- and 5-minute Apgars. The results supported the measure's validity and are discussed in terms of implications for practice and further research to explore TMBT's usefulness.