If you've ever asked for a bigger budget and gotten a polite no, you know the problem: "we need more books" or "we need more staff" competes against hospitals, roads, and clean water, and usually loses. The argument feels true to you and abstract to everyone holding the budget.
There's a better argument available, and it isn't a trick: it's already written into a framework most governments have formally signed onto.
It's literally in the text
The UN's 2030 Agenda for Sustainable Development sets out 17 Sustainable Development Goals covering poverty, education, health, gender equality, and more. Access to information is written directly into that framework: SDG Target 16.10 calls for ensuring public access to information as part of building peaceful, inclusive, accountable institutions. Libraries aren't a stretch-interpretation fit for this goal; they're a literal one.
That matters because it changes the shape of the ask. You're not requesting a favor. You're asking your institution or government to follow through on a commitment they already made.
Not theoretical: already running
IFLA directly supported "The 2030 Arab Librarians," a project led by the Arab Federation for Libraries and Information (AFLI) to build an online course specifically on libraries and the SDGs. A related advocacy training run by IFLA's MENA Regional Division with AFLI enrolled 45 librarians from public and university libraries across 17 Arab countries; 19 completed the full three-month program and became advocates for the approach in their own libraries. That's a reasonable completion rate for asynchronous, multi-country training, not a discouraging one.
What this looks like in practice
The strongest version of this argument is narrow, not broad. Pick two or three SDGs your library's actual work clearly supports, then build a one-page case with four parts: the specific goal, the concrete service that supports it, the specific gap funding would close, and one clear ask.
A funder can say yes to "$1,200 for 10 tablets to expand our homework support program, which served 340 students last term." It's much harder to say yes to "please support the library."
This is exactly what the free module, Libraries & the SDGs: Making the Case for Support, walks through, including an interactive builder that turns your own library's work into a first-draft funding case.