The “Car-Free Day” is a worldwide activity aim to encourage people following “In town without my car!” and making a change towards more sustainable transport modes. The events of car-free day serve as opportunities for participating cities to show how environmental issues concern them. Local authorities can present their urban in a different light and implement key actions aiming at restricting motorized traffic in certain areas, encouraging the use of sustainable modes of transport and raising awareness on the environmental impacts of citizens’ modal choices. 2008 Taipei International Car-Free Day focus on the issues of “Clean Taipei” and “Green Transportation”. Major events of this year’s activities including biking festival, public transportation week, and the implementation of car-free area at Xinyi Business District on Monday, etc. A before/after analysis was executed for the event of car-free area at Xinyi Business District. The results showed travelers’ behavior changes significantly due to executing of car-free projects. Some of car drivers hand in their driving licenses during that day. Also, most of the air quality and noise indicators showed positive results, proving that the activity indeed was effective in lowering air pollution. Through these events, the city hopes to involve more residents in taking a closer look at transportation options. People will realize that over usage of motorized vehicles, such as motorcycles and automobiles, will create a significant impact upon our environment. By raising their awareness, we hope residents will choose green vehicles and public transportation to help preserve our planet.