I was born/raised Presbyterian (PCUSA) and I became Catholic my senior year of college.
(Put those eyebrows back down, there are a lot of us out there!

)
My thought process on the subject started my junior year. With college came a bit more personal responsibility and some analysis of how I grew up and where I wanted to go. When I looked at the church I was raised in, I saw a good bit of doublespeak: claiming to base their doctrine on the principle of
sola scriptura , but their policies often contradicted that. It's one thing to have challenges come up that make it difficult to be consistent, but there were some instances that were just blatant w/out apology.
In addition, I got to meet people who were Catholic and very serious about their faith - so much so that they could explain reasonable and complete answers to questions I had. It turns out everything that I had learned about "what Catholics believe" from my well-meaning Presbyterian pastors was wrong.
In the end, I decided that Catholicism just made more sense and was historically more consistent w/ Scripture than the protestant denominations. I was received on Easter Vigil in 1990.
Adrienne (PNAM-2003)