People in New York City walk more – both longer distances and more trips – than people in any other major metropolitan area in the United States. Why is this so? The principal goal of this dissertation is to explain why New Yorkers walk more than residents of other cities. Using self-reported survey data, Geographic Information Systems (GIS), and the discrete choice model, this study will specifically examine four questions: 1) What factors determine whether New York City residents choose to walk – both for their work and their nonwork trips? 2) What factors explain where New York City residents choose to live, focusing on the role that neighborhood walkability plays in this decision? 3) What factors explain whether or not New York City residents own a vehicle, focusing on the relationship between car ownership and the choice to walk? 4) How closely linked are the choices to walk, own a car, and live in a pedestrian-friendly neighborhood? A secondary goal of this project is to develop a state-of-practice model for planners and policy analysts.