Library School

So back when I was an undergrad I worked in the library on campus in the circulation department. In the normal course of events you get to talking with people and you come to find out how the people who work full time came be doing that.
For the most part librarians have gone to library school. At this point in time "library school" means a masters program at an institution accredited by the American Library Association (ALA). There are undergraduate programs that will prepare you for a masters program but there is currently (that I am aware of) no bachelors degree in Library and Information Science. As you may know, not all librarians have MLS degrees. There are many who have become librarians through years of experience.
What does the word "librarian" mean then? The term is quite specific actually. A library is just like any work place, there are different jobs that make it run. Generally speaking, a librarian is a rank within the organization and not a general job title for every person who works at the library. Library's have library assistants, volunteers, people who work in library systems (computers or "IT"), and those who work in acquisitions and cataloguing. Most likely each area has a coordinator (maybe called a dept. head or supervisor) and that person could have the title of librarian, but not always. Sometimes, there is only one position that is actually called "librarian." This means many things but most often it means you get paid more for what you do. Make no mistake, a title means nothing in terms of how much work you do.
What you notice in looking at job descriptions is that a position with the word "librarian" attached to it demands not just credentials but experience. Like many jobs they require that you bring something to the table in order to deserve what you are being offered.
What is common practice is to address someone who may not have the official title of librarian, as a librarian. I am officially a Reader Advisor, that is what you will see on my job description. If you ask anyone who knows me, I am a librarian. My boss is the Regional Librarian for Massachusetts. There is only one librarian here at BTBL in this case (note: we are not the only two people here).
So there's a bit of information for you, ask me about my job some day, I'll be happy to tell you (maybe another entry...)