Visa requirements for American passport holders
Short Stay Visa Requirements: up to 90 days
American passport holders are not required to obtain a visa prior to visiting France for up to 90 days in any 180-day period.
As of October 18th, 2013, the rules for calculating short stays within the Schengen area have changed. More details and a calculator online on the European Commission website. Visitors who intend to work in France do need to obtain a work authorization or get their "convention d’accueil" prior to their arrival in France.
Long Stay Visa Requirements: more than 90 days
American passport holders are all required to obtain a visa to spend more than 90 days in France.