Some publishers ask for sole consideration of your proposal. In my process, I have mostly given sole consideration to the publishers to whom I have been proposing.  This has been largely a product of my approach: as discussed in previous posts, I feel that it’s best to write a distinct proposal for each publisher, to better match their list. Because that’s a pretty big effort, I don’t send out a lot of proposals at once. In August, I sent out one proposal that never earned any response, so I suppose that I wasn’t quite offering sole consideration on the two proposals I sent after that. Because it takes time to move from one proposal version to the next, and because the responses I did receive were generally quick (on 3 out of 5, I received a response within a day or two), I was basically offering sole consideration: as soon as I got a positive response, I focused my energies on responding to that one publisher, and not one making a proposal for another.