The information below will be of use to non-EU citizens traveling to Europe from countries that offer reciprocal visa arrangements (visa waiver or visa exemption programs). These include Canada, the United States, Australia, New Zealand and some Asian, South American and Central American countries. Full lists of countries requiring visas and countries with visa exemptions can be found online.
The maximum length of stay in Europe for non-European Union passport holders is determined by the Schengen accord and is currently limited to 90 days within any 6 month period (we have changed this recently from 180 days to 6 months in light of new information received, despite the fact that many sites report 180 days as the limit). The important thing to note is that you may not leave the Schengen Visa area for a day and return to restart the 90-day clock. If you've spent 90 days in the Schengen zone, you're done for a six month period. Travelers holding US passports should refer to the US Department of State Schengen Fact Sheet, for updated information.
Who Needs a Schengen Visa?
According to the Consulate of France in Houston "No Visa is required for a short stay not exceeding 3 months in a Schengen State for tourism or business purposes for the applicants of the following countries:
Andorra*, Argentina, Brazil, Bulgaria, Canada, Chile, Cyprus, South Korea, Czech Rep., European Union* and EEA (Germany, Austria, Belgium, Denmark, Finland, France, Greece, Iceland, Ireland, Italy, Luxembourg, The Netherlands, Norway, Portugal, Spain, The United-Kingdom (until December 31, 2020 when the Brexit transition period has ended), and Sweden), Hong-Kong (only passport issued by the HKSAR), Hungary, Israel, Japan, Liechtenstein*, Macao (only passport issued by MSAR), Malta, Mexico, Monaco*, New Zealand, Poland, Romania, San Marino*, Slovakia, Slovenia, Switzerland*, The Holy See*, Uruguay and USA."
(Note that Switzerland, which belongs neither to the EU nor to the European Economic Area, has had the same visiting limits as Schengen and is set to implement the Schengen rules, together with Liechtenstein, by the end of 2008)
The citizens of the countries above marked with the sign * do not need a visa for a long stay.
Source: General Consulate of France in Houston
[Note: They mean that passport holders from the above countries traveling for purposes of tourism do not have to apply for a Schengen visa, because those countries have reciprocal visa agreements. You will still be operating under the rules of the Schengen visa.]
New Zealand is a special case. According to safetravel.govt.nz, "New Zealand has bilateral visa waiver agreements with many of the individual countries in the Schengen area. These visa waiver agreements allow New Zealanders to spend up to three months in the relevant country, without reference to time spent in other Schengen area countries." A list of countries is found at the link above.
Europe Outside of Schengen
An exception to the 90 day Schengen visa scenario occurs when visiting the non-Schengen UK, where US, Canadian, and Australian nationals are given a 6-month visa upon entering. This visa does not apply to the Schengen area.
Europe for 1 Year: Do I Need a Schengen Visa?
The above is the title of a Travellerspoint forum post that has a lot of information in it for those who wish to try to stay away from home for a longer period of time than the permitted 90 days.
The above information was believed to be accurate when written. It is not intended as legal advice. As with all agreements, terms can change over time. More countries will be added to the list of Schengen countries as they join the EU. Check the visa resources above if you have questions about longer stays in a European country.