BACKGROUND: As the global under-five mortality rate declines, an increasing percentage is attributable to early neonatal mortality. A quarter of early neonatal deaths are due to perinatal asphyxia. However, neonatal resuscitation (NR) simulation training in low-resource settings, where the majority of neonatal deaths occur, has achieved variable success. In Bihar, India, the poorest region in South Asia, there is tremendous need for a new approach to reducing neonatal morality. METHODS: This analysis aims to assess the impact of a novel in-situ simulation training program, developed by PRONTO International and implemented in collaboration with CARE India, on NR skills of nurses in Bihar. Skills were evaluated by clinical complexity of the simulated scenario, which ranged from level 1, requiring NR without a maternal complication, to level 3, requiring simultaneous management of neonatal and maternal complications. A total of 658 nurses at 80 facilities received training 1 week per month for 8 months. Simulations were video-recorded and coded for pre-defined clinical skills using Studiocode™. RESULTS: A total of 298 NR simulations were analyzed. As simulation complexity increased, the percentage of simulations in which nurses completed key steps of NR did not change, even with only 1-2 providers in the simulation. This suggests that with PRONTO training, nurses were able to maintain key skills despite higher clinical demands. As simulation complexity increased from level 1 to 3, time to completion of key NR steps decreased non-significantly. Median time to infant drying decreased by 7.5 s (p = 0.12), time to placing the infant on the warmer decreased by 21.7 s (p = 0.27), and time to the initiation of positive pressure ventilation decreased by 20.8 s (p = 0.12). Nevertheless, there remains a need for improvement in absolute time elapsed between delivery and completion of key NR tasks. CONCLUSIONS: PRONTO simulation training enabled nurses in Bihar to maintain core NR skills in simulation despite demands for higher-level triage and management. Although further evaluation of the PRONTO methodology is necessary to understand the full scope of its impact, this analysis highlights the importance of conducting and evaluating simulation training in low-resource settings based on simultaneous care of the mother-infant dyad.