Mary Cummings is the founder of Great River Literary, a boutique agency devoted solely to children's and teen publishing, with deep relationships across the major houses and a particular strength in picture books and middle grade.
In brief
Great River Literary is exclusively children's and teen — no adult projects under any circumstances.
The client roster and sales record reveal consistent strength in picture books (board books through concept books) and middle grade chapter books, with imprints like Knopf, Philomel, Viking, Balzer & Bray, and Feiwel & Friends appearing repeatedly — signaling real editorial relationships at Penguin Random House and Macmillan in particular.
Multiple clients have sold more than one book through Cummings (Ariel Bernstein's Warren & Dragon series, Angela Dalton's two titles, Elizabeth Verdick's bilingual board books, Joy Keller's picture books), suggesting a preference for authors with series or multi-book potential rather than one-offs.
The wishlist emphasizes historical fiction and fantasy grounded in reality for middle grade, found family, and friendship stories — categories less prominently represented in the current confirmed sales record, which skews picture book-heavy, meaning MG manuscripts may have more room on the list right now.
Cummings spent thirteen years at another agency before launching Great River in 2021, bringing an established editorial network to an intentionally small, focused operation — queries benefit from that boutique context.
Lately
Cummings describes the agency's relationship network as producing a 'rapidly growing list of sales,' citing deals with more than twenty named imprints and houses — a signal that the list is still actively expanding rather than at capacity.
What Mary is looking for
This is Cummings's most documented strength by sales volume. Concept books, rhyming stories, humor, and celebration narratives all appear in the confirmed deals. Author-illustrators should include a link to a dummy and sample spreads; text-only authors should paste the full manuscript in the email body. No attachments.
Cummings has sold bilingual English-Spanish board books and concept board books, and the agency's own description explicitly includes this format. Particularly open to nonfiction concepts and social-emotional themes for the youngest readers.
Cummings names middle grade as a top priority across several flavors: contemporary friendship and found-family stories, magical realism, fantasy rooted in the real world, and historical fiction where the period carries genuine narrative weight. The wishlist signals an appetite for literary middle grade with emotional depth, not just plot-driven adventure — though commercial middle grade is explicitly welcome too. Chapter books with series potential (see the Warren & Dragon books) are also in scope.
YA is within scope but less prominently foregrounded on the wishlist and less represented in confirmed sales. Literary YA and YA with historical or fantastical elements are the most likely fits given the stated taste profile.
Poetry appears in the genre list and Cummings represents it, but it is not singled out as an active priority. Strong, distinctive voices with a clear audience age range are the safest bet.
Nonfiction for young readers — including art, history, and humor — is on the list. History-focused nonfiction is welcome when the subject matter carries real consequence for the intended readership. Nonfiction picture books are explicitly included.
Cummings specifically calls out historical fiction and historical fantasy as favorite sub-genres, with the condition that the period must matter to the story — not just window dressing. Fantasy that is grounded in realistic emotional or cultural truth is equally welcome.
Not the right fit
On Mary's list
Taste fingerprint
How to query Mary
Send the full picture book text pasted into the body of the email — never as an attachment. Author-illustrators should include a URL to a dummy and sample illustrated spreads instead of attaching files.
For chapter books, middle grade, and YA, paste only the first three pages in the body of the email. Do not attach a full manuscript.
Include a brief project description, a short author bio, any relevant publishing or writing experience, and any background working with children — Cummings explicitly says that context is helpful.
Great River Literary represents children's and teen work only. Do not mention or reference any adult projects, even in passing.
The wishlist favors warmth, wonder, and emotional grounding — pitches that foreground found family, friendship, or a protagonist's sense of belonging are likely to resonate more than those leading with plot twists or darkness.
For historical fiction or historical fantasy, make clear in the query why the specific time period is essential to the story — Cummings has stated that the period must carry real consequence, not serve as mere backdrop.
If pitching a concept or series, note the series potential briefly — the sales record shows a consistent pattern of multi-book relationships with clients.
Expect no response unless the project is a potential fit — Cummings states they reply only to queries that may be a match, so the absence of a reply is a soft pass.