The editor of the online magazine Slate, Jacob Weisberg, announced a publishing partnership yesterday with the Perseus Books Group and Atlas Books, whose president is James Atlas. The series of paperback originals will make its debut in June, with the goal of publishing several titles a year.

“The three of us sat in a big room and made a list of everything a publisher does, and divided it among the three of us,” the president and CEO of Perseus Books Group, David Steinberger, said. “This is a unique arrangement.”

It’s so unique that there’s already some confusion about which entity will take on which roles. Mr. Steinberger said Perseus would take care of “copyediting, getting it printed, and handling inventory.”

Mr. Weisberg, however, said in a separate interview that Slate would handle its own copy. “We’re going to do the copyediting; we can do that easily.”

But the parties seem to be in agreement on the general division of labor.

Mr. Atlas, who was the founding editor of the Penguin Lives series of short biographies, will edit the series. He said the role of Atlas Books will be editing material that has “incubated” on Slate and generating new ideas for the Web site that could be expanded into books. “It was attractive to me because it’s younger authors than I’m used to working with,” Mr. Atlas said. “It’s a new medium, and it’s fun.”

Aside from copyediting – maybe – Perseus will take on production and distribution. “We’re providing services for the books to be published,” Mr. Steinberger said, “but the key creative decisions reside with Jim Atlas and Jacob Weisberg. We’re in the service business.” Perseus acquired Client Distribution Services, an independent book distributor, last year.

Mr. Weisberg said the advantage to Slate is that the partnership “reflects what we’ve tried to do with Slate. As compared to the conventional way, we want to do something that is quicker, more nimble, more spontaneous.” He said the model would allow a book to be on shelves just months after it is conceived, as opposed to the usual one-year lead-time required in publishing.

Slate’s previous books, including the 2004 collection “The Explainer,” have been published individually with various publishing houses. The new series will be designed individually but will share a “matched format,” Mr. Weisberg said.

The first book in the series, “The Best of Slate: A 10th Anniversary Anthology,” will be published in June. Edited by Slate’s deputy editor, David Plotz, it will have a print run of 45,000. Mr. Weisberg will write the introduction; the founding editor, Michael Kinsley, will provide the foreword, and the book will features contributions by Christopher Hitchens, Michael Lewis, Atul Gawande, and Marjorie Williams.

Other titles will include “The Wall Street Defense Manual,” by Henry Blodget, and the anthology “Backstabbers, Crazed Geniuses, Animals We Hate – Slate Writers Tell It Like It Is.”