Writing an EOI for a Collaborative Grant

An Expression of Interest (EOI) is the first-stage narrative in a two-stage grant competition — most commonly used for large, multi-partner collaborative research funding, such as Horizon Europe two-stage calls (where it is formally labelled an “outline proposal”) and UKRI’s large-grant and lead-agency schemes. A funder that expects far more consortium bids than it can fully peer-review asks every applicant to submit a short, high-level EOI first; only the strongest subset is then invited to prepare the full, detailed second-stage proposal. Writing a competitive EOI is a distinct skill from writing a full proposal, and it is also a genuinely different document from a federal Letter of Intent or a foundation Letter of Inquiry — conflating the three is a common, avoidable mistake for research administrators moving between funding sectors.

How an EOI differs from a Letter of Intent and a Letter of Inquiry

All three documents sit “before” a full proposal, which is why the terminology gets blurred in practice. The mechanisms, and the stakes, are not the same:

Expression of Interest / outline proposal (this page) — used almost exclusively for large, competitively oversubscribed, multi-partner collaborative grants. It is substantively evaluated: a review panel scores the scientific/technical case on a subset of the full award criteria, and only a limited proportion of EOIs advance to stage two. The document itself is a compressed version of the actual research narrative, not an administrative notice.
NSF Letter of Intent — a short, non-binding, administrative notice required only when a specific NSF solicitation asks for one. It is not scored and does not determine whether the subsequent full proposal will be accepted for review (only whether it is accepted at all, if a required LOI is skipped). It carries none of the actual scientific narrative.
Foundation Letter of Inquiry — a competitive screening document, but built for single-organization applicants approaching a private, family, community, or corporate foundation. It has no consortium-composition dimension, no work-package structure, and no blind-review convention, because the underlying grant it precedes is not a large multi-institutional collaboration.

The practical test: if the funding opportunity involves a multi-institution consortium, a competitive oversubscription ratio the funder is actively managing, and a stage-one document that is genuinely peer-reviewed on scientific merit (not just logged for planning purposes), you are almost certainly dealing with an EOI/outline-proposal mechanism, not an LOI in either of the other two senses.

Where the EOI mechanism is used

Horizon Europe two-stage calls — a first-stage outline application (commonly capped around ten pages) is submitted by the stage-one deadline. It is evaluated against only two of the three standard Horizon Europe award criteria — Excellence and Impact — leaving Implementation for stage two. First-stage Part B narratives are evaluated blindly: applicants may not disclose the identity of the coordinating or partner organizations within the scored narrative text itself. Because the funder is managing a specific oversubscription target for stage two (typically aiming to admit roughly two-and-a-half to three times the available budget’s worth of proposals, so the panel has a real, but not overwhelming, pool to select the final awards from), the threshold for advancing is calibrated to that ratio each call, not fixed in advance.
UKRI large-grant and lead-agency schemes — several UKRI research councils run an explicit outline/EOI stage ahead of an invited full application, including large-grants competitions in specific disciplinary councils and joint lead-agency opportunities run with international partners (for example, NSF-UKRI lead-agency calls, where the two agencies jointly review the EOI before inviting a full proposal from either side). As with Horizon Europe, only applicants shortlisted at the outline stage are invited to submit a full application; an uninvited full submission is typically not accepted.
Other multi-partner and center-scale competitions — large national and international consortium programs elsewhere frequently borrow the same two-stage logic even where the terminology differs (outline, pre-proposal, concept note). The structural conventions below generalize across most of them; always confirm the specific call’s own template and page/word limits before treating any general guidance as authoritative for your call.

What an EOI is evaluated on — and what it isn’t

The defining feature of the EOI stage is a deliberately narrowed evaluation scope, not a shrunk version of the full evaluation:

Scientific/technical excellence and novelty — the core research question, its originality relative to the state of the art, and the soundness of the proposed approach at a high level.
Impact and pathways to impact — who benefits from the results, how, and why the consortium (described functionally, not by named institution where blind review applies) is positioned to deliver that impact.
Not evaluated at this stage, typically: detailed implementation planning, a full work-package-by-work-package resourcing breakdown, governance and risk-management structures, a complete data management plan, or a fully itemized budget. Those are stage-two material. Writing them into an EOI wastes scarce page allowance the panel needs for the two criteria that are actually being scored, and on Horizon Europe calls specifically, over-detailing implementation in a blind-reviewed Part B risks inadvertently identifying the consortium.

Structuring the EOI narrative

Exact templates vary by funder and call — always follow the call’s own outline-application template and page/word limit over any general structure — but a competitive EOI for a large collaborative grant conventionally covers:

Concise project summary — the research question and its significance, stated in language a cross-disciplinary panel (not just specialists in your sub-field) can follow, since first-stage panels are often broader than the specialist panel that reviews stage two.
State of the art and novelty — what currently exists, and precisely what gap or opportunity this project addresses that existing work does not.
Objectives — a small number of clearly stated, high-level scientific objectives; this is not the place for a full objective-by-task breakdown.
Outline approach / high-level work plan — the major phases or work packages at a summary level (typically named and one-line-described, not resourced in detail), enough for a panel to judge feasibility without the implementation depth that belongs in stage two.
Consortium composition and complementarity, described functionally — under blind review (Horizon Europe Part B), this means describing the roles and expertise types the consortium brings (“a partner with established capability in X,” “a coordinating group with a track record in Y”) without naming institutions in the scored narrative; where blind review does not apply, this section instead names partners and states each one’s role and complementary strength explicitly.
Impact pathway — treated as its own distinct argument from scientific excellence, not folded into it: who uses the results, what changes as a result, and over what timeframe.
Indicative budget envelope — a total requested amount or range, not an itemized budget; itemization is stage-two work.

For the surrounding award-lifecycle terminology, see the CASRAI Dictionary’s entries on the Data Management Plan (typically deferred to stage two on most two-stage schemes) and the grants management pillar for the broader pre-award workflow this fits into.

What changes between the EOI and the invited full proposal

Implementation detail — full work-package resourcing, Gantt-style timelines, and risk/mitigation planning appear only at stage two.
Named partners and letters of commitment — where stage one used functional, non-identifying consortium descriptions (blind review), stage two names every partner explicitly and typically requires formal letters of commitment or support from each one — these are essentially never required at the EOI stage.
Full budget and budget justification — an itemized, per-partner budget with justification replaces the stage-one budget envelope.
Compliance documentation — ethics self-assessments, full data management plans, and institutional sign-offs are stage-two requirements on most schemes, not stage-one ones.
Evaluation criteria — the full set of award criteria (on Horizon Europe, Excellence, Impact, and Implementation) applies at stage two; the EOI is scored on a deliberately narrower subset.

An invitation to submit a full proposal is not a funding decision — it means the outline cleared a competitive first screen, sized to the funder’s oversubscription target for that call, and the full proposal is then reviewed on its own merits against the complete criteria set.

Common mistakes

Writing the EOI as a shrunk full proposal. Cramming implementation detail, a full budget, or partner letters into a document scored on excellence and impact alone wastes the limited page allowance on content the panel isn’t evaluating at this stage.
Naming institutions in a blind-reviewed narrative. On Horizon Europe two-stage calls, disclosing identifying information in the scored Part B text is a real compliance risk, not a stylistic choice — check the specific call’s rules on what may and may not appear in the blind-reviewed sections.
Treating impact as an afterthought. Because Implementation is deferred to stage two, Excellence and Impact carry the entire first-stage score between them — an EOI that spends nearly all its space on scientific novelty and only a sentence on impact is competing at a real disadvantage against one that argues both cases fully.
Omitting the budget envelope. Even without itemization, panels use the requested amount to judge scale and feasibility fit against the call’s available budget; leaving it out or stating it vaguely makes that judgment harder to make in the applicant’s favor.
Assuming the same template applies across funders or even across calls from the same funder. Page limits, blind-review rules, and which criteria are scored at stage one all vary by call — always confirm against the specific call document rather than reusing a previous EOI’s structure unchanged.

Frequently asked questions

Is an EOI the same as a Letter of Intent?

No. An EOI for a large collaborative grant is substantively peer-reviewed on scientific merit and determines whether a consortium is invited to submit a full proposal. An NSF Letter of Intent, where one is required, is a non-binding administrative notice used for review planning and is not scored on merit.

How is an EOI different from a foundation Letter of Inquiry?

A foundation letter of inquiry screens a single applicant organization against a foundation’s funding priorities. An EOI for a large collaborative grant additionally has to establish a multi-partner consortium’s complementarity and, on schemes like Horizon Europe, do so under blind-review rules that restrict naming institutions in the scored text — a structural requirement foundation LOIs don’t have.

How long should a stage-one EOI or outline proposal be?

It varies by call and must be confirmed against that call’s own template; Horizon Europe two-stage outline applications are commonly capped around ten pages for the narrative (Part B). UKRI large-grant outline stages typically use a shorter, structured online form rather than an open-format document. Always follow the specific call’s stated limit rather than a general norm.

What happens if my EOI is not selected to advance?

The consortium is not invited to submit a full proposal in that call. Because the number of EOIs invited to stage two is deliberately sized against the funder’s available budget for that competition, a strong project can still miss the cut in a highly oversubscribed round; funders generally do not provide the same depth of individualized feedback at this stage that a full-proposal review provides.

Can I name consortium partners in a Horizon Europe stage-one outline proposal?

Not in the scored, blindly reviewed sections of Part B under Horizon Europe’s two-stage evaluation rules — consortium composition is instead described functionally, by role and expertise type. Confirm the exact scope of the blind-review restriction against the specific call’s submission guidance, since implementation details differ by call.

For related pre-award writing conventions, see the guide to NSF Letter of Intent requirements, the guide to foundation letters of inquiry, and the grants management pillar for the broader proposal-development workflow.