The paper introduces the Systems Engineering Initiative for Patient Safety (SEIPS) model, a framework for understanding the structures, processes, and outcomes in healthcare and their relationships. The SEIPS model integrates Donabedian's structure-process-outcome (SPO) framework and the work system model, emphasizing the impact of work system design on patient safety, employee outcomes, and organizational outcomes. The model is applied to outpatient surgery to identify safety threats and plan interventions. The paper also discusses the model's practical and research applications, highlighting its potential to guide system design, hazard analysis, and patient safety research. Key messages include the importance of balancing the work system to consider the needs of all stakeholders and the influence of work system design on patient and employee outcomes.The paper introduces the Systems Engineering Initiative for Patient Safety (SEIPS) model, a framework for understanding the structures, processes, and outcomes in healthcare and their relationships. The SEIPS model integrates Donabedian's structure-process-outcome (SPO) framework and the work system model, emphasizing the impact of work system design on patient safety, employee outcomes, and organizational outcomes. The model is applied to outpatient surgery to identify safety threats and plan interventions. The paper also discusses the model's practical and research applications, highlighting its potential to guide system design, hazard analysis, and patient safety research. Key messages include the importance of balancing the work system to consider the needs of all stakeholders and the influence of work system design on patient and employee outcomes.