ISO/IEC 15504 provides a framework for the assessment of processes. This framework can be used by organizations involved in planning, managing, monitoring, controlling, and improving the acquisition, supply, development, operation, evolution and support of product and services. The published ISO/IEC 15504 process assessment models for systems and software do not currently provide a sufficient basis for performing a process capability assessment of processes with respect to the development of complex safety-related systems. Developing safety-related systems requires specialized processes, techniques, skills and experience. Process amplifications (safety extension) are needed in the area of safety management, safety engineering and safety qualification. ISO/IEC TS 15504-10:2011 presents these amplifications (a safety extension) as three process descriptions: safety management, safety engineering and safety certification processes. The aim of ISO/IEC TS 15504-10:2011 is not to provide a way to verify the compliance with one or more domain-specific safety standards, nor to extend ISO/IEC 15504 in order to use it as a safety standard against which to verify compliance. The aim is to provide assessors with the necessary means and information for measuring the capability of processes and also defining possible process improvement actions when the software/system under development is safety-related. ISO/IEC TS 15504-10:2011, as a standalone document, can be used in conjunction with ISO/IEC 15504-5 and/or ISO/IEC TR 15504-6 process assessment models by experienced assessors with minimal support from safety domain experts. ISO/IEC TS 15504-10:2011 is developed independent of any specific safety standards that define safety principles, methods, techniques and work products. However, elements of relevant safety standards are able to be mapped to the safety extension and the safety extension is intended to be extendable to include specific safety standards requirements. The influence of the safety extension on the assessment of the processes in ISO/IEC 15504-5 and ISO/IEC TR 15504-6 is described in ISO/IEC TS 15504-10:2011. For each process contained in ISO/IEC 15504-5 and ISO/IEC TR 15504-6, there is an indication of additional issues to be taken into account at assessment time. The issues are provided by means of sentences indicating specific relationships between ISO/IEC 15504-5 and ISO/IEC TR 15504-6 processes and the ISO/IEC TS 15504-10:2011 processes as well as highlighting relevant aspects to be considered to improve the completeness of the data-gathering phase of the assessment. In this way, an assessor can use ISO/IEC TS 15504-10:2011 to check whether, in assessing an ISO/IEC 15504-5 or ISO/IEC TR 15504-6 process, some relevant aspects related to the safety development environment have been missed.