I was offered a full-time position as prevention assistant for a local substance abuse agency, having only a BA in Psych and Sociology. This covers three counties, and I would be fourth in command within the department. Not bad for an -almost- college graduate. Degrees are important. Networking is even better. But I do think a Master's is helpful for moving up the ladder, especially with more college graduates than ever before.
Edit: I should have mentioned that I did an internship with the agency first. It was about two months in, and the director approached me about the job. I declined the offer, but she is still a very helpful resource.