If you've spent any time researching foundation funders, you've probably encountered the letter of inquiry (LOI). Some foundations require one before they'll accept a full proposal. Others use them as the primary application. A few treat them as optional. And many nonprofit professionals, especially those newer to grant development, aren't entirely sure what distinguishes a letter of inquiry from a short proposal, or why the distinction matters.
It matters more than it might seem.
A letter of inquiry and a full grant proposal are doing different work at different stages of a funder relationship. Treating one like a shortened version of the other is one of the most common mistakes organizations make, and it tends to produce letters of inquiry that don't get invited to submit full proposals.
What a Letter of Inquiry Actually Is
A letter of inquiry, often called an LOI, is an introductory document. Its job is to give a funder enough information to determine whether your organization and program are a potential fit for their funding priorities. It's not an application. It's an opening.
Most letters of inquiry run two to four pages. Some foundations specify a page limit or a word count. Some provide a template or a list of questions they want addressed. Whatever the format requirements, the fundamental purpose is the same: to answer, concisely and compellingly, whether what you do aligns with what the funder funds.
The funder uses the LOI to screen for fit before investing review time in a full proposal. You should use the LOI to assess that fit too. Writing an LOI is not just about getting invited to submit. It's also about figuring out whether submitting is worth your organization's time.
How a Letter of Inquiry Differs from a Full Proposal
The most important structural difference is scope. A full grant proposal builds a complete argument. It documents community need with data, describes the program in detail, presents an evaluation plan, establishes organizational qualifications, and includes a full budget. It's a comprehensive document that gives a reviewer everything they need to make a funding decision.
A letter of inquiry does none of that in full. It introduces the need, sketches the program concept, signals organizational credibility, and makes a case for why this funder in particular should want to learn more. It's persuasive writing, not comprehensive documentation.
The tone tends to differ as well. A full proposal follows a structured format with distinct sections. An LOI reads more like a letter, because it is one. It should be direct, clear, and specific, but it should also feel like the beginning of a conversation rather than the submission of a file.
Budget treatment is another difference. Most LOIs don't include a full budget. You'll typically mention the total funding request and sometimes provide a brief budget overview, but the detailed line-item budget and budget narrative belong in the full proposal.
What a Strong Letter of Inquiry Needs to Include
Even within the shorter format, certain elements are essential. Funders making screening decisions need enough information to assess fit. A letter that's too vague to evaluate isn't helpful to them, and it won't advance your application.
A clear statement of the problem. What community need are you addressing, and why does it matter? You don't have the space for a fully developed needs statement, but you need enough specificity that the funder understands the problem and why it's worth addressing in the community you serve.
A description of what you're proposing to do. What is the program or project? Who does it serve, and how? What outcomes are you working toward? This doesn't need to be exhaustive, but it needs to be concrete. Vague program descriptions in an LOI rarely generate invitations to submit.
Your organization's qualifications. Why is your organization positioned to do this work? This is usually brief, two to four sentences that establish your track record, your community relationships, or your specific expertise. The goal is credibility, not a full organizational history.
The funding request. How much are you asking for, and over what time period? Most funders want this information in the LOI. Be specific.
Why this funder. This is where many LOIs fall short. A letter that could have been sent to any foundation is less compelling than one that reflects genuine knowledge of this funder's priorities and makes a clear case for alignment. Reference specific program areas, geographic interests, or strategic priorities the funder has articulated. Show that you've done your homework.
The Most Common LOI Mistakes
Writing a compressed version of a full proposal. When organizations try to fit everything into the LOI, the result is usually a dense, hard-to-read document that doesn't communicate clearly at the introductory level. The LOI isn't a shorter proposal. It's a different document with a different job.
Being too vague about the program. Some organizations go the other direction and keep the program description so high-level that the funder can't get a clear picture of what the work actually involves. There's a balance between introductory and specific. Aim for enough concrete detail that a reviewer understands what you're proposing to do and for whom.
Ignoring the funder's specific questions or format requirements. If a foundation provides an LOI template or a list of questions to address, follow it exactly. Submitting a letter in your preferred format when the funder has specified their own is a compliance problem that signals you didn't read the guidelines carefully.
Treating the LOI as less important than the full proposal. Because it's shorter, the LOI can feel like a preliminary step that doesn't warrant full attention. But for many funders, the LOI is the decision point. If it doesn't generate an invitation to submit, there is no full proposal. It deserves the same care as any other proposal document.
Missing the relationship dimension. An LOI is an introduction. The best ones read like the beginning of a relationship, not a transaction. That doesn't mean being informal or casual. It means writing to a specific funder about a specific alignment, in a way that communicates that you understand who they are and what they're trying to accomplish in the world.
When a Funder Doesn't Require an LOI
Not all foundations use the LOI process. Some accept unsolicited proposals directly. Some have open application cycles with no preliminary screening step. But even when an LOI isn't required, the thinking behind it is useful.
Before you invest the time in a full proposal, it's worth asking the same questions an LOI would force you to answer: Is this funder's focus genuinely aligned with what we do? Do our program and budget fit within their typical grant range? Have we reviewed their recent awards to confirm that organizations like ours have been funded? Is the timing right?
The LOI is a tool for mutual assessment. Using that assessment process, even informally, before committing to a full proposal application saves time and tends to produce stronger applications when you do submit.
A Note on Unsolicited Letters of Inquiry
Some organizations send LOIs to foundations that haven't specifically invited them, as a way of initiating contact and gauging interest before putting a full proposal together. Whether this is appropriate depends on the funder.
Many foundations have clear guidelines about whether they accept unsolicited inquiries. Some don't. If a foundation's website or guidelines don't address it, a brief phone call or email to program staff is a reasonable way to ask before investing time in a letter they may not read.
When unsolicited LOIs are appropriate, they follow the same general principles as any LOI: be specific about the program, make the case for alignment with the funder's priorities, and keep it concise. The difference is that you're opening a door rather than walking through one that's already open.
The letter of inquiry is a distinct skill from proposal writing, and it's worth developing deliberately. Getting it right means understanding what the document is supposed to accomplish, building it around what a funder actually needs to assess fit, and treating it as the beginning of a relationship rather than a hurdle to clear on the way to the real application.
When that framing guides the work, the letter of inquiry becomes one of the more useful tools in grant development.
The Grantsmanship Center has been training nonprofit professionals in the fundamentals of grant proposal writing since 1972. Learn more about our training programs at tgci.com.
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