sara,
Since I was born and raised in Virginia, I have studied the Civil War in some detail. I studied under one of the preeminent Civil War scholars (Robertson) at Virginia Tech.
While it would be wrong to say the Civil War wasn't about slavery, this particular issue was a smaller one within the context of a disagreement over states' rights. It was a major "growing pain" in the relatively new Union, with the predominantly agrarian southern states fighting for more power, while the industrial north favored a stronger union.