Falls Church’s George Mason High School could expect another bump-up in enrollment based on journalist Jay Mathews’ latest “Challenge Index” results published in today’s Washington Post.

GMHS ranked fourth among the top 172 high schools ranked by Mathews using his unique “Challenge Index” measure, and that resulted in the Falls Church City School System being ranked first among school districts in the greater Washington, D.C. metro region, overall.

According to Mathews, “The Challenge Index measures a public school’s effort to challenge all of its students. The formula is simple: Divide the number of Advanced Placement, International Baccalaureate or other college-level tests a school gave in 2009 by the number of graduating seniors. Tests taken by all students, not just seniors, are counted.”

Mathews notes that the D.C. region, overall, are the “most encouraging of college-level testing,” when compared with schools across the U.S. A total of 145 D.C. area high schools are among the top six percent of schools in the nation in encouraging students to take AP, IB or Cambridge tests.

Only Arlington’s H-B Woodlawn, Montgomery County’s Richard Montgomery and D.C.’s Columbia Heights high schools ranked higher than George Mason High School.

“I’m so proud of our students and staff at George Mason High School,” FCCPS Superintendent Lois Berlin said in a press release today. “They continue to challenge themselves to reach their greatest potential, and it shows in the results.”

The last time GMHS and the Falls Church school system were ranked so high by Mathews in the Challenge Index, in the late 1990s, the result was a significant boost in enrollment in the Falls Church system.