Six Sigma has been adopted by many software development organizations to identify problems in software projects and processes, find optimal solutions for the identified problems, and quantitatively improve the development processes so as to achieve organizations' business goals. A Six Sigma framework for software process improvements is needed to provide a standard process and analysis tools for Six Sigma project executions, and also provide a platform for collaborations with other process improvement approaches, such as PSP/TSP and CMM/CMMI. However, few frameworks have been proposed to support Six Sigma project executions. Most of Six Sigma projects for software process improvements have been performed in an ad-hoc way. In this paper, we propose a framework to support Six Sigma projects for continuous process improvements for software developments. Based on this framework, we implemented a web-based tool, called SSPMT integrated with a software project management tool and a PSP...