Understanding the factors associated with successful funding outcomes of research project grant (R01) applications is critical for the biomedical research community. R01 applications are evaluated through the National Institutes of Health (NIH) peer review system, where peer reviewers are asked to evaluate and assign scores to five research criteria when assessing an application's scientific and technical merit. This study examined the relationship of the five research criterion scores to the Overall Impact score and the likelihood of being funded for over 123,700 competing R01 applications for fiscal years 2010 through 2013. The relationships of other application and applicant characteristics, including demographics, to scoring and funding outcomes were studied as well. The analyses showed that the Approach and, to a lesser extent, the Significance criterion scores were the main predictors of an R01 application's Overall Impact score and its likelihood of being funded. Applicants might consider these findings when submitting future R01 applications to NIH.