The respondent list for the 2007 Census of Law Enforcement Gang Units was developed through phone consultations with all law enforcement agencies having 100 or more sworn officers. The 534 agencies that reported having at least one officer dedicated solely to dealing with gang problems received the survey instrument via email, fax, or U.S. Postal Service, depending on their stated preference. Data collection occurred from April of 2008 through April of 2009 with a nearly 90% response rate. After the removal of all out-of-scope respondents that did not qualify as having a gang unit, the final dataset included approximately 400 units.