Hey, SWP author here.

As others have said, they're a co-op publisher focusing on MG and YA, and have recently launched imprints for romance and adult spec-fiction.

My book is an adult romance originally published under the SWP banner, but now moving to their romance imprint, Caleo Press.

If you're ever considering self-publishing I greatly suggest you doing so with SWP. As it's a co-op publisher, you retain your rights and royalties, but as part of the co-operative, you'll get marketing help and a community of authors to assist you, in exchange for doing the same for them - i.e. featuring a link to similar books in the back of your books, sharing sales on social media etc.

They're a lovely bunch. I published my own book with them, and am certain it wouldn't have been half as successful without their help.

You'd need to upload your own book to Amazon, and you'd be completely in charge of it, but they can supply you with an ISBN at a discounted rate (otherwise, if you wanted to sell via Ingram it costs about $1000 for ISBNS) and they will help you with marketing, feature your books in catalogues they send out to libraries and other important places, and if you want you can attend conventions they have a table at or send your books for others to sell on your behalf at the convention.