Although many studies have shown that reviewers particularly value the feasibility of a proposed project, very little attention has gone to how applicants try to establish the plausibility of their proposal’s realization. With a sample of 335 proposals, we examined the ways applicants reason the feasibility of their projects and the kinds of evidence they provide to support those assertions. We identified three kinds of evidence for mastering research: the scope of scientific skills, the presence of different assets, and the use of stylistic techniques. Applicants draw on them to align the project with scientific standards, embed it in the current state of research, and meet the scientific field’s expectations of how scientists should conduct a project. These kinds of evidence help substantiate a project’s feasibility and to distinguish the project from other proposals. Such evidence seems to correspond with a project’s positive review and approval (grant success). Evidence of research mastery was cited more often by the authors of the successful (approved) proposals than by the authors of the unsuccessful ones. The applicants of the successful proposals gave details of their planned experiments, emphasized their broad methodological and technical competence, and referred to their own preliminary scientific work.