I had a pop star feature published in a children’s magazine two years ago. I read about a call for biography submissions from a children’s book publisher and I think that my feature would fit in with what they’re looking for. Since it was first published in a magazine, can I submit it to a book publisher?
Rights are rights. There’s no difference between selling rights to a magazine and selling rights to a book publisher. It depends on whether or not the magazine owns all rights. Assuming you still have the contract you signed when you originally sold the piece, you should be sure to read it over again. If the contract is for nonexclusive serial rights and the rights revert to you after publication, then you are free to submit your manuscript to other markets, including book publishers.
If the contract is for all rights, then the text of the article belongs to the magazine. Moira Allen covers the issue of re-selling your published work in her article, Can I Sell a Previously Published Article?
There is a fairly straightforward way around the copyright issue. But it will involve some serious re-writing on your part. Since your article was written and published a couple years ago, it could probably use some updating. In fact, even if you own the rights, you should re-visit the work, dust it off and spice it up. Do some research for new information about your subject that you can add to beef up and revise the original text. Think up a new title.
Go to your local library and/or bookstore and look at the biographies published by the publisher you plan to submit to. Then use your published article as a basis for an updated, improved biography that will fit in well with the style of books they publish.