"We are excited to acquire a young player like Cristian, who we feel is one of the most talented players in El Salvador," General Manager Dave Kasper said. "He has performed well at the club level and certainly established himself as one of the most important players on the national team in the recent World Cup qualifying campaign. Cristian has excellent speed and technical ability, and will be an exciting addition to our midfield."
The 25-year-old Castillo has 32 total caps with El Salvador since making his debut on April 23, 2008.
D.C. has along history of attracting Salvadorans, dating back to Raul Diaz Arce from its championship teams of 1996 and 1997.
Salvadorans form the largest immigrant community in the Washington area.