Abstract: Capability Maturity Model Integration (CMMI) is a quality model used in the development of many products. Software products differ from other types of products because they are intangible; evolve quickly and with no physical forms. To assure the quality of developed software a good quality model should be applied. One of the good models is CMMI. CMMI generally used in large-scale firms but it may be customized to use in small and medium firms. In this research, we are going to find the impact of using CMMI practices on the success of small and medium software firms. The results showed that there is a real problem in these firms regarding software process improvement (CMMI). Most firm’s staff have no knowledge about CMMI. They did not know how it would help in producing high quality software. The research results will help small and medium firms to compete in software development industry, help them also in adopting high quality models in their development process.