Independently from which software process was selected for a company or a project, the selected software process usually cannot be applied without any customization. Although the need to tailor a software process to specific project requirements seems to be widely accepted and unquestioned, the way of doing the tailoring remains unclear and is, therefore, often left to the expertise of process engineers or project managers. What are the criteria to be applied in the tailoring? What are dependencies between different criteria and how should certain criteria influence the software process? In this paper we investigate concrete tailoring criteria for the tailoring of software processes. To this end, we present a collection of 49 tailoring criteria as the outcomes of a systematic literature review. We further analyze the impact of the discovered tailoring criteria by relating them to a set of 20 exemplary tailoring actions, which affect the projectspecific software process. Our outcomes show that the factors influencing the tailoring are well understood, however, the consequences of the criteria remain abstract and need to be interpreted on a project-per-project basis.