Mr. Castillo graduated with his English degree from Texas Tech University in 1994. Shortly after, he accepted a teaching and coaching position at Dumas Jr. High in Dumas, Texas. He taught 7th grade English and coached 7th grade girls athletics.
In July of 1996, Mr. Castillo accepted a teaching position in Lockhart, Texas. There he was a 9th grade English teacher and coached high school girls basketball and volleyball. In the summer of 1998, Mr. Castillo became the Lockhart Lady Lion Head Girls Basketball Coach and Girls Athletic Coordinator. He took a varsity basketball program that had won a total of 10 games the previous two years, to a 19 -11 record and a state play-off berth in his first year . His three year coaching record reflected 56 wins and 29 losses.
In December of 1999, Mr. Castillo earned his Masters Degree in Educational Administration from Southwest Texas State University. In December of 2001, Mr. Castillo accepted an Assistant Principal position at Judson High School. At the time, Judson High School was a Nationally Recognized Blue Ribbon High School and a New American High School.
In January of 2004, Mr. Castillo was promoted to Associate Principal at Judson High School. As Associate Principal, Mr. Castillo supervised 10 administators and counselors and over 125 professional employees and more than 25 paraprofessional employees. He supervised the master schedule, professional development, instructional programs and the budget for the high school. In 2004, Judson High School's student enrollment was over 4600 students.
In July of 2005, Mr. Castillo was hired as Assistant Principal of Poteet High School. The following year he became the Principal of Poteet High School. He served as principal until October 2009, when he took over as Superintendent of Schools.