The NSF GRFP provides three years of funding. Students can apply before starting graduate school or within the first two years of graduate school, assuming that you have not received any prior graduate school credit. Look at the guidelines carefully, as the details are very specific as to the number of graduate credit hours you can have completed. You must be a US citizen to apply.
Like all NSF grants, the application will be judged based on intellectual merit and based on broader impacts. To excel at intellectual merit, you want to have a history of previous research experience and a well conceived, hypothesis drive research proposal that ties to your research interests. This proposal does not have to be what you will do as a graduate student, but should reflect your capacity to design compelling research. To excel at broader impacts, you will benefit from discussing any past experience that you have in mentoring students, in conducting science-based outreach and in communicating science to the public. You need to present a plan to conduct outreach and training of others while you are in graduate school. This will benefit from learning about programs available at your institution that facilitate outreach and student training.
Some Specific Comments
- When you apply, you will be expected to indicate that field or fields most related to your research. While you can indicate two or more fields, it is most likely that your proposal will go to the panel that you say is most associated with your work.