This paper describes the work done during the past two years by USC, in collaboration with its Corporate Affiliates and the INCOSE Measurement Working Group, to develop the initial version of COSYSMO. The paper focuses on the need for the model, describes how it was developed, summarizes its initial architecture, and identifies the size and cost drivers that participants in the model design thought to be significant. These were identified through a series of Delphi surveys where experts were asked to provide their opinions. The paper concludes with a summary of the results of these Delphi surveys and a discussion of future steps that need to be taken to guarantee COSYSMOs successful adoption by the Systems Engineering community.