Software process improvement is an important activity which starts when an organization plans to enhance/purify the capabilities of its ongoing processes. When improvement or change is planned or started, there are a number of factors which originate and affect the effectiveness of software process improvement. If they are not identified and dealt with proper expertise, they can leave adverse effects in the form of low effectiveness, high cost, low quality etc. Such factors change the intensity or the expected results of software process improvement. It is very important to understand and highlight these factors in order to make the process improvement effective and efficient in an organization during change. This master thesis is written to answer the research questions which elaborate the understanding of software process improvement and factors affecting the software process improvement during change in an organization. Moreover, a systematic review is also performed in identifying and prioritizing the factors which affect the software process improvement activity in change. The outcomes of this research can be helpful in understanding the factors affecting SPI during change.