In order to drive in Poland, American citizens must have either an international driving permit (IDP) or a Polish national driver’s license: a U.S. state driving license without an IDP is insufficient. Americans may use an IDP until it expires, regardless of the date of entry into Poland. In the U.S., you can obtain an IDP from any local AAA; if you are currently overseas, send the completed application to:

AAA/IDP
Mailstop # 28
1000 AAA Dr.,
Heathrow, FL 32746 USA.

For more information on the IDP, click here: http://www.aaasouth.com/travel_drivers.asp
For an application, click here. http://www.aaany.com/travel/travel_services/IDP_1.htm

American citizens applying for a Polish drivers license are now required to pass a written examination (non-Polish speakers must provide their own licensed interpreter) and pay the examination fee. 

Additionally, you must bring to the examination center:

-an application for exchange of a driver’s license
-a receipt for the driver’s license issuance fee
-a sample signature
-a photograph
-an authorized translation of your U.S. state driver’s license
-a photocopy of the state driver’s license
-Upon receipt of the Polish driving license, a foreigner must submit his state/national license to the local licensing office.  The Polish authorities will subsequently send the foreign license to the Consulate with a request that it be returned to the licensing authority in the United States. If you have questions about this procedure please call the Consulate at: (012) 424-5122.