In order to adopt specific agile methods and to accommodate lean principles, many organizations need to tailor their processes. Different frameworks supporting and guiding the agile transition and adoption process exist in the literature. However, there is a demand for specific guidelines on the different circumstances influencing agile adoption. This paper provides a Systematic mapping of the available frameworks, issues and factors affecting a successful agile transition and adoption process. Twenty-eight primary studies have been considered. The results are presented according to the three research questions. Firstly, nine systematic approaches and frameworks for agile transition and adoption are analyzed. Secondly, different issues related to the agile transition and adoption process are gathered, compared and synthesized in the following five categories: pre-transformation activities, obstacles and results, stages and activities, agile practices and situational factors. Finally, a list of 154 situational factors affecting the agile transition and adoption process is proposed.