David Lyons has been coaching the St. Mark’s cross country team since 2005. Over that time, the team has enjoyed considerable success at both the varsity and junior varsity levels.

Both teams have had winning records every year for more than a decade. The varsity’s regular-season record since 2005 has been 149 wins against only 41 losses. The JV's record has been even better: 168 wins and 23 losses. The varsity won ISL and New England Championships in 2011 and 2013, as well as additional New England Championships in 2006 and 2007 (and second place finishes in 2008, 2009, and 2010). Last year, the team finished second in the sixteen-team ISL. The JV won ISL titles in 2015 and 2016, as well as New England Championships every season from 2006 to 2009 (finishing second in 2005 and 2010). St. Mark’s also has had a number of runners recently go on to compete in college at schools like Colby, Hamilton, Connecticut College, Lewis and Clark, Kenyon, and Hobart.

David Lyons came to St. Mark's after practicing labor and employment law at Ropes & Gray in Boston, clerking for Judge Bruce M. Selya on the U.S. First Circuit Court of Appeals, and teaching history at St. Andrew's School in Middletown, Delaware. He graduated from the University of Virginia (JD, MA) and Harvard (BA), where he lettered in baseball and played on the freshman football team. He has taught a variety of courses at St. Mark's (most recently Advanced American History, Advanced American Government, AP European History, and The Atlantic World). Outside of the classroom, he is the head coach of the boys’ cross-country program and an assistant coach to the varsity baseball team. He lives on campus with his wife and four children. In his free time, he enjoys running, golf, hiking, and playing with his kids.

Rob is an alumnus of St. Mark's, Class of '04. After graduating from Wake Forest University and teaching at Groton School for one year, Rob returned to St. Mark's in the fall of 2009. At St. Mark's, Rob has taught American history, Economics, the Middle East Since 1800, Our Times and Postwar America, in addition to coaching the boys' cross-country and baseball teams. He lives on campus with his family.