Software Process Improvement (SPI) has become the key to the survival of many software development organizations. Many international SPI models/standards, such as; ISO, Capability Maturity Model Integrated (CMMI), SPICE, Trillium…etc, are developed for SPI. Numerous software development companies have chosen to utilize CMMI to access and improve their current software development process, because CMMI is one of the most widespread and acknowledged SPI models. Unfortunately, CMMI does not provide a systematic way of determining how to improve the process. That is, CMMI defines "what to do" but leaving "how to do it" to organizations. Thus, it is desirable to have a means to guide the companies in the development of action plans and appropriate tools for SPI. These actions should be based on the software process requirements from relevant sources. Therefore, this research proposes a SPI-CMMI framework that provides an overall process improvement strategy to be implemented in any software development organization more effectively and comprehensively. The proposed model based on applying assessment and improvement procedures through adopting the CMMI-DEV 1.3 model using six sigma approach and Quality Function Deployment (QFD) technique.