Inherent safety is a concept particularly used in the chemical and process industries. An inherently safe process has a low level of danger even if things go wrong. It is used in contrast to safe systems where a high degree of hazard is controlled by protective systems. It should not be confused with intrinsic safety which is a particular technology for electrical systems in potentially flammable atmospheres. As perfect safety cannot be achieved, common practice is to talk about inherently safer design. “An inherently safer design is one that avoids hazards instead of controlling them, particularly by reducing the amount of hazardous material and the number of hazardous operations in the plant. Inherent safety is a proactive approach for loss prevention and risk management. Considering the lifetime costs of a process and its operation, an inherent safety approach can lead to a cost-optimal option. Inherent safety may be achieved at any stage of process design; however, its application at the early stages of process design yields the best results. Despite being an attractive and cost-effective approach, the inherent safety methodology is not widely used. Many reasons have been attributed to this lack of widespread use; the nonavailability of systematic tools for the application of inherent safety principles is perhaps the most important reason. This paper presents a conceptual framework of an integrated inherent safety index (I2SI). It is called an integrated index because the procedure, when fully developed, is intended to consider the life cycle of the process with economic evaluation and hazard potential identification for each option. The I2SI is composed of subindices which account for hazard potential, inherent safety potential, and add-on control requirements. An application of the I2SI is also discussed. © 2004 American Institute of Chemical Engineers Process Saf Prog 23: 136–148, 2004 An inherent safety index may be divided (for example) into two subindices: chemical inherent safety index and process inherent safety index. These subindices may also be further divided into other subindices. Chemical inherent safety index covers parameters related to hazards presented by the chemicals in the plant, and process inherent safety index deals with the hazards due to equipment and inventory in the plant. Scores are given for subindices based on the parameters of the individual components. Calculated by adding all the subindices together, the resulting total inherent safety index can be used to compare the safety of different designs. A lower score indicates safer design. Nevertheless, the original inherent safety index method has its own limitations as will be illustrated in the case study. An enhanced inherent safety index method was proposed by the research team to enhance its functionality. (Ref. Xiang Li, Anand Zanwar, Abhishek Jayswal, Helen H. Lou, and Yinlun Huang, Industrial & Engineering Chemistry Research (Article - dx.doi.org/10.1021/ie101660q |Ind. Eng. Chem. Res. 25 Jan 2011, 50, 2981–2993), Incorporating Exergy Analysis and Inherent Safety Analysis for Sustainability Assessment of Biofuels, Michigan, USA 2011)