Neighborhood Security Act of 2003 - Authorizes the Attorney General, through the Office of Justice Programs, to award grants to nonprofit organizations and professional associations to develop and improve Neighborhood Watches throughout the Nation.

Requires grants to be used to: (1) complete a survey that identifies Neighborhood Watches by ZIP code; (2) establish a national registry of Neighborhood Watch leaders; (3) identify best practices and model programs among Neighborhood Watches for preventing and responding to terrorism and crime; (4) create a manual for communities seeking to establish or improve a Neighborhood Watch; (5) engage in outreach and respond to inquiries to disseminate information about the benefits of effective Neighborhood Watches and the means to establish or improve them; and (6) provide a Neighborhood Watch start-up kit upon request.