on Publishing … and Other Forms of Insanity:
Here are twenty publishers seeking nonfiction. They are looking for a wide range of subjects, including art, theater, children’s nonfiction, calendars, memoirs, pop culture, politics, history – in short, if it isn’t fiction, they want it.
All are traditional publishers, and none require an agent.
Unlike fiction, in which writers are asked to either submit a sample of their writing or a full manuscript, nonfiction writers are required to submit a proposal. Proposals typically run about 25 pages. They contain an overview, a detailed table of contents, a bio of the author, a business plan, a competitive title analysis showing which similar books are already on the market and why yours is better, and sample chapters.
The proposal is essentially a quick guide to your book that will enable a publisher to decide whether it is worth their time and effort, so make sure you spend time and effort writing your proposal.