Organizations always try to improve processes, optimize workflows and minimize turnover rate in order to enhance efficiency, increase productivity, reduce waste and improve performance. Process improvement is a vital component for organizations and it can be achieved through a variety of quality methods, such as, total quality management, Lean, Six Sigma and etc. Process improvement begins with complete understanding of current processes which requires data analysis, stakeholder engagement followed by an implementation with proper methods. Soft Systems Methodology (SSM) is a perfect problem-solving approach to analyze complex processes and to find suitable implementations. This paper uses SSM in software development process (SDP) within two interrelated organizations. In this research, SSM applies some problem-solving techniques, such as systems thinking, rich picture drawings, root definition and related systems construction, conceptual model creations and action planning to maintain continuous process improvement. This thesis study contains four sub-processes of SDP. These sub-processes are called Design Management, Technical Development, Testing and Training processes. Seven-staged SSM is applied to sub-processes in order to enhance system performance. Last stage of SSM, which is action taking, is presented however it is not applied yet. Apart from this, rich pictures of sub-processes are drawn, relevant systems and root definition are identified, conceptual models are created with focus group studies. Lastly, suggestions are offered regarding to real world activities and conceptual models. Results of study shows effectiveness of SSM for ill-structured problems in SDP. It emphasizes real world activities and proposes needed activities in sub-processes to overcome issues in SDP.