Purpose The purpose of this Allied Environmental Conditions and Test Publication (AECTP) is to describe the process known as the Ten Step Method which has been developed to determine the ability of materiel to meet extended life requirements. The process is presented in this AECTP which is a framework document. The purpose of this framework document is to acquaint project (program) managers with the engineering principles involved when evaluating the implications of extended life requirements@ and also with the outline of a management tool that systematically addresses the issues to be resolved. It is intended that this framework document will be enhanced in due course by additional guidance to assist the serious practitioner. Application The process described in this AECTP is applicable to all materiel projects. It is especially applicable to joint NATO materiel projects and multi-national materiel projects. Although the process is comprehensive and could@ on initial examination@ be considered excessive@ it does ensure that all appropriate environmental conditions@ possible failure modes and earlier qualification assumptions have been considered. Moreover@ streamlining and early exit criteria are integrated systematically into the process. Limitations The application of the process is limited to materiel where life is a function of exposure to environmental stresses. In addition to life extension requirements@ the Ten Step Method can accommodate minor role and deployment changes. However@ the process requires further development to incorporate major role and deployment changes@ munitions@ new materiel development programmes and new off-the-shelf acquisitions. It is planned to include these developments in Edition 2.