 On August 7, 2006, the Washington Nationals acquired Chico and fellow minor league pitcher Garrett Mock from Arizona in a trade for veteran right-handed pitcher Liván Hernández.After joining the Nationals organization, Chico pitched for the Harrisburg Senators of the Class AA Eastern League, winning 2 and losing none of his first 4 starts and compiling a 3.27 ERA.At the end of 2006, Chico had earned a spot on the Nationals' 40-man protected roster.