Skip to main content
U.S. flag

An official website of the United States government

Activity codes—why not R01 and only R01?

NIA Blog Team Avatar

NIA Blog Team

An R01 research project grant is the dollar bill of NIH. It is our most recognized award, our most common award, our most flexible award, and our most understood award. So why is it not our only award?

Well, we have training mechanisms, fellowships, career development awards, scientific meeting grants, awards for small businesses, centers, and even construction awards (elsewhere at NIH). So certainly we need to name these programs differently and different strings of letters and numbers make sense.

But what about research activities? We have R03s, R13s, R15s, R21s, R33s, R34s, R41s and R42s, R43s and R44s, R45s, R56s, and P01s, not to mention U01s, U19s, and the out-there UH2s and UH3s (No, that is not some kind of sterilized milk or stealth bomber!) What gives with all that?

R versus U grants

It makes sense to separate our normal research grants (R series) from the cooperative agreements (U series), in which NIH staff have a substantive role in the research along with the investigators. So the “R” versus “U” distinction captures that.

R03s and R21s and P01s

  • An R03 is a small grant.
  • An R21 is an exploratory/ developmental award.
  • And a P01 is a complex mechanism in which a program leader works with several investigators, each of whom has a sub-project within the overall program project.

Why not just have small R01s, big R01s, and exploratory R01s?

Let’s start with the R03. (Here’s an R03 announcement that we participate in.) This mechanism helps differentiate a small project from an undersized R01. NIH supports research awards for up to 5 years at a time and provides substantive awards to researchers to make major advances. Sometimes, you have a small project, and submitting it as an R01 can send the wrong signal. Why? Because reviewers will expect big results from your small project. Instead, while an R03 does accomplish important work, it doesn’t have the heft of an R01 in review. R03s (and R21s!) are reviewed separately from R01s. So, having the different activity code helps to distinguish it and protect it from perhaps misdirected comments that the work does not substantially advance the field. At NIA, we find the R03 particularly useful for secondary analyses of existing data—an increasingly important area of research.

The R21 is an exploratory/developmental award. (And here’s an example of an R21 announcement.) Really the birth of this one is a function of what reviewers expect in R01s. In the past, if applicants proposed a method that was not well-established, a test that was not well-validated, an animal model that had not proved itself, or even a conceptual model that had not seen much sunlight, the application was dinged in review. “How can we be certain that the research will work if the method, test, or animal or conceptual model proves invalid?” asked reviewers. In turn, many applicants saw that criticism as contributing to a scientifically conservative bias in review. “How can we make progress if we cannot use new tests, methods, or models?” they asked.

And so the R21 was born. And we at NIA are not so confident in our current tools that we can’t benefit from the introduction of new ones. On the contrary, we see that as our lifeblood. I wrote a blog post about why the NIA supports R21 grants not too long ago.

And the P01 program project grant? (An example of an NIA P01 announcement.) Sometimes, researchers want to mount a complex interdisciplinary attack on a complex public health problem. The projects are sufficiently diverse that a standard panel of reviewers has insufficient expertise. Yet, the work benefits from having common cores shared among the projects and each project has the potential to shed light on the science in the other projects. The whole then is greater than the sum of the parts. At NIA, we have found P01s particularly useful to us because aging itself is a complex issue that does not affect one organ or tissue or cell but has system, person, and even societal effects.

So, the bewildering varieties of activity codes serve different functions. NIH has a complete list of every kind of activity code that’s used anywhere in the organization, if you want to read more.

I hope that that tale of the origins and purpose of these codes helps you think through what will work for your research project. Still, your best strategy is to share your ideas with a program officer. If you can’t identify the right program officer, you can start by contacting me.


Read Next:

Misused and misunderstood terms: NIH is a foreign language

An official website of the National Institutes of Health