You should first contact child protection services in your local state and find out if you are entitled to collect past due support. You should also obtain information on how to collect back unpaid child support.
YOU can't get it. Your mother would have to push it. You aren't entitled to it, she is. Since your grown, what's the point? Did your dad know you were born? Sometimes women want children and sleep around til they get pregnant.... They don't always want a man in their life to mess things up. I'd find out all the facts if you have to get into something that isn't your business anyway. Oh, and way to go welcoming your dad into your life like this.
Knuckleburg...Im sure if your father was out of the picture for 20 years you'd want some restitution for his absence! and don't say you wouldn't. That is being a dead beat father and ANY dead beat father should be sued for back child support from grown children. Bridgette..Most states had laws that govern that. I'd go talk to a attorney or a family law specialist. :) TO hell with dead beat dads...Good luck with everything!