My wife and I are having marital problems. She wants to take our 3 small children and move to another state. Can I stop her?

Yes, file for a divorce. If there is no paperwork either one of you can take the children pretty much anywhere.

Or, if you still hope to save the marriage, you might want to consider filing for separation, with an order controlling custody, visitation, and child support. But it's important that you understand that, without such an order in place, if she does take the children and go to another state, once she has been there for six months, child custody would be decided in the courts of that other state.

Basically, you both have equal rights until a court orders otherwise. So you have to file for either a separation or divorce and file for primary custody of the children.