John graduated from Dartmouth College in 1986 and soon after moved back to his native Argentina to work in the Marketing and Strategic Planning Office of Techint in Buenos Aires until 1989. He started teaching Spanish at Hotchkiss as a sabbatical replacement in 1989, and in 1990, he and his wife Mercedes moved to Deerfield; from 1990-96, John taught Spanish and coached soccer and squash at the Academy. In 1997 he obtained a master's degree in education from Columbia University as part of the Klingenstein Program.
John was named Academic Dean at Deerfield in 1998 and then moved to Buenos Aires, Argentina from 2000-05 to become the Head of St. Andrew's Scots School, a private K-12 IB school for 2,000 students. He returned to Deerfield in 2006 and has been the Dean of Faculty and Associate Head of School since September 2007. Mercedes, his wife, teaches Spanish and art at Deerfield; his daughters, Sofia and Maia, graduated from Deerfield in 2013 and 2015 respectively.