Reviewers are on a need-to-know basis

I recently reviewed a faculty member's grant application. It was a cool project! I could understand the importance, I had examples of application, I got the gist of how it would be carried out, etc. Only trouble was, there were quite a few paragraphs of technical information that I couldn't understand. Normally, this would be expected since many grant applications must include technical language to show reviewers, who are experts in the field, that you're on the cutting edge. However, the intended sponsor for this grant stated that they had laypeople on their review committee. So, I as a layperson reviewing this grant was a comparable reviewer.

All of this to say that when it comes to grant-writing, less is more. Your challenge is to write to your audience (your reviewers) as concisely as possible to clearly convey the great importance of your project and offer just enough justification and technical details to convince them you will be successful... and that's it! So, seems simple enough, but there are variables to consider as you decide what needs to go into and stay out of your grant application.

Who are your reviewers?
To figure out what your reviewers need to know, you need to first have a sense of who they are. Are they laypeople or experts? Are they in your field or not? Are they familiar with you or your area? To answer these questions, explore the website of your sponsor. Some sponsors will list their reviewers and some will describe the background of their reviewers. Sponsors will also describe the level of detail and background information they expect in their program announcement or grant application guide. Not surprisingly, to know what to tell them, we must first know who reviewers are.

What do they need to know?
Once we have a sense of who our reviewers are, we can then start to formulate what they need to know to make a decision on your project. No matter who they are, you always want to emphasize the importance of your work and the impact your work. You must also convince your reviewers that you will be successful in carrying out your project.

How do you best convey your project?
The language you use to convince your reviewers will vary based on your reviewers. For reviewers who are experts in your field, you'll want to demonstrate your knowledge of the field and relevant scholarship. However, make sure that you are careful that your discussion of the field doesn't get too tangential to your project. Stay focused, show your expertise, and bring it back to your compelling case. Start with your case and end with your case. For laypeople, you'll also want to convince them that you and your project are the way to go, but you'll need to use jargon-free and plain language to show them.

It may sound harsh to say, but at the end of the day, if your grant proposal doesn't speak to your reviewers in whatever way, it's your fault. If you didn't know who they would be or what they needed to know, it's of no use to blame them for that. If your grant is rejected, use the reviewer comments to better understand them as an audience so you can better write for them when you resubmit.

Resources:
Confessions of a Grant Reviewer - Margaret Ring
Crafting a Sales Pitch for Your Grant Reviewer - Robert Porter