Today’s software industry is tasked with building evermore complex software applications, and multiagent system technology is a promising approach capable of meeting these new demands. Unfortunately, multiagent systems have not been widely adopted in industry for reasons that include lack of industrial strength methods and tools to support multiagent development. Method engineering, an approach to constructing processes from a set of existing method fragments, has been suggested as a solution to this problem. This chapter presents the Organization-based Multiagent Software Engineering (O-MaSE) methodology framework, which integrates a set of concrete technologies aimed at facilitating industrial acceptance. Specifically, O-MaSE is a customizable agent-oriented methodology based on consistent, well-defined concepts supported by plug-ins to an industrial strength development environment, agentTool III. O-MaSE is defined, and demonstrations of customizing O-MaSE for the CMS problem as well applying the customized process to the CMS design are presented.