You must be licensed by the state in which you work before you can begin practice.
Here are resources to help you with licensing:
Names and contact information for all state and territory licensing boards.
You can learn at a glance what your state requires for licensing (PDF).
Here are five tips to help your licensing process run as smoothly as possible.
A summary that lists which states require topic-specific CME for license renewal (PDF).
This page includes summaries of all state PA laws and regulations.