I know that you have to gain experience in another position before you can become a game designer. For example, I would probably start as a programmer or a writer and keep working until i climb the ranks and show my abilities, etc. But how exactly does this process work? How easy is it to get from one department to another, or observe or work with another department? How do you "prove your worth" as a designer when you're working as a programmer?

Moving up the ladder is more a Breaking In question, so I'm moving this.
I wrote some articles about moving up the ladder -- in my monthly IGDA column, "The Games Game."
For instance:
Playing the Upgrade-To-Designer Game (April 2006)
http://www.igda.org/games-game-april-2006

Quote: Original post by livesmart247
But how exactly does this process work? How easy is it to get from one department to another, or observe or work with another department? How do you "prove your worth" as a designer when you're working as a programmer?

The general advice is to do the job, and then your career will follow it.

For a programmer that means discussing designs with other designers, attending optional meetings about the design of your game, spending time providing careful feedback, getting involved in discussions and providing meaningful contributions, and otherwise being proactive about doing the design work you crave. As you do this, you will be included in more design discussions. Being included in additional discussions will give you additional opportunity to do design work. The cycle will repeat as long as you nurture it.

After you have proven that you have the ability to do the job and have outgrown the basic tasks, your career will follow.

Quote: Original post by livesmart247
I know that you have to gain experience in another position before you can become a game designer.

This isn't true from my experience in the industry. Unless "junior designer" counts as another position.

Quote: For example, I would probably start as a programmer or a writer and keep working until i climb the ranks and show my abilities, etc.

If anything you'd start in a different *design* role - e.g. a level designer, puzzle designer, board-game designer, etc... rather than an unrelated field, like software engineering.

From my personal experience, related both to my career and someone else's, it just happens so to speak.
If people know your interest, and you provide them with hard work in your field and they can see a hint of your usefulness, they will get you closer to what you want in due time. I've seen a programmer, aiming for top level design position get there in an instant when the spot was empty. He was hardworking, and had always shown interest for the post. Worked like magic. Why? Hardwork.