Introduction: The sensitivity of newborns and children to exposure to available environmental stimuli is directly related to infant neuropsychomotor development, as it is influenced by both biological and environmental factors. The environment can provide both positive and negative stimuli. In this context, the Neonatal Intensive Care Unit (NICU) represents an atypical environment that disrupts the relationship between parents and the baby and provides unusual sensory experiences due to frequent procedures that can cause pain, exposure to noise, excessive light, and mechanical ventilation. Currently, there is no instrument that assesses these elements by qualifying and grading their risks or benefits. The International Classification of Functioning, Disability, and Health (ICF), used in focused forms like CORE SETS and Checklists, can be applied with the objective of classifying and allowing the evaluation of environmental factors involved in the NICU. Objective: To develop an Environmental Factors Checklist based on the ICF for the neonatal intensive care unit (NICU). Methodology: This study is a cross-sectional type, characterized as expert research, based on WHO guidelines and the ICF research department's guidelines for developing a CORE SET. Healthcare professionals from various fields with experience in the NICU will be recruited to answer a questionnaire with sociodemographic questions and open-ended questions about environmental factors in the NICU setting. Subsequently, the responses will be linked to the ICF categories and domains. Expected Results: We aim to develop a reliable and valid tool for classifying environmental factors involved in the neonatal intensive care unit (NICU) space.