This subject has come up a lot recently with several of my publishers, so I thought I'd give new writers a heads up.
Simultaneous submissions means that you submit (send) your story to more than one publisher at the same time.
Publishers hate this. If they invest the time to read your story and prepare to put it into their publication schedule or anthology, they don't like to find out later that you sold it somewhere else. they get grumpy about it, and probably won't bother to read anything else you submit to them. Ever.
Writers feel that they increase their chances of selling a piece, and selling it faster, if they submit to all potential markets at the same time. Some publishers are notoriously slow about responding, and some don't bother responding at all if they're not interested, which leaves the writer wondering for months on end if it's safe to send the story out to someone else. That's pure rudeness on the publisher's part, and the industry is rife with it.
So what is a writer to do?
You might be chomping at the bit to get your story published, but unless you write highly topical books, your words aren't going to go stale. So have some patience, and some class. Unless a call for submissions specifically states that simultaneous submissions are okay, assume they aren't. Send your story to your dream publisher* first. If they say they'll be back to you in four weeks, and it's been five, send a very respectful letter** asking if they received your submission and when you can expect to hear back from them. They will probably admit that they passed. At that point, send it to your second choice. If they don't respond to the polite note, assume rejection and move on. If they do suddenly say yes later, you covered your ass with the note and they don't have the right to get huffy about you sending out to a different publisher. I'd caution you against working with anyone who shows such poor communication skills though - especially someone in the media business.
So to recap - submit to only one publisher at a time, no matter how tempting it is to send to more than one. Simultaneous submissions = bad reputation.
* I'll talk about dream publishers in my next blog.
** respectful letters do not include demands, threats, diva attitude, or anything else that will warn a publisher that you're a nitwit who will be a pain in the ass to work with. Strangely enough, in most cases, diva attitude is in inverse relationship to talent.