Active street events originated as ciclovias in Bogota, Colombia, as a day to promote free health and community oriented events.  In these events, a popular section of streets are closed to automobile traffic and community members are encouraged to bike, walk, or play within the streets.  In 2011, St. Louis, MO held two St. Louis Open Streets events modeled after ciclovia to highlight the assets of the city and encourage residents to be physically active.  The purpose of this project was to develop a strategy to increase urban youth and family participation in St. Louis Open Streets events and to evaluate the effect of the promotion strategies on participation levels.  Key informant interviews were used to identify effective community-based communication strategies to promote the events and potential routes.  Participation levels were assessed with direct observation.  Results aimed to help inform the St. Louis' Mayor's Office with policy decisions on future ciclovia events.