I wanted to know, do I need an agent to get my book published?
-- Kim, Toronto
Great question! And the answer is relatively straightforward -- mostly. It all depends on the goal you have in mind for your book. Are you aiming to have your book in print with a traditional New York publisher? Or have you written something that doesn't quite fit in the "traditional publishing" box, ie. a novella? Maybe something written in an unusual style? For the former, you more than likely will need representation, but for the latter, you probably won't (by this I mean epublishers, independents, self-publishing, etc.). The easiest way to find out would be to check the publisher's submission requirements. In our current online world, this is not difficult to do. All of the houses have an online presence where they will explicitly outline exactly what they want to see.
And an important point of note here: the guidelines are there for a reason. You can't assume that they don't apply to you, for whatever reason. Blatantly ignoring a house's guidelines is the quickest way to the rejection pile that I know. It's also the first step in building the wrong sort of reputation in the publishing industry. (If he/she can't follow simple submission guidelines, what is he/she going to be like to work with later?)
So how do you find that agent? One word: research. There are many reputable, hard-working agents out there, and there are unscrupulous ones as well. Word-of-mouth is a great tool. Also, finding agents who represent authors who write in a similar style or genre to you could also be helpful. Just be cautious before you sign your name on that dotted line.
And whatever you decide to do, good luck!