Feffie coached lacrosse for 20 seasons at the College of William and Mary, Williamsburg, VA and accumulated a 157-87-1 record. Here she led her teams to 6 NCAA tournament appearances and 7 Conference titles. While coaching at William & Mary she coached 26 All- Americans and 9 US Team players.

Feffie was also active as a coach for the US Lacrosse Squad program and her coaching was highlighted by a Gold Medal at the 1989 World Cup in Perth Australia. She has been a Coach and Clinician for several other countries including Japan, Canada and Scotland. She also introduced lacrosse in South Africa.

Following her term as President of US Lacrosse, Inc. Feffie focused her work on helping to create the US Lacrosse, Inc. Coaches Education Program. This program is now available and servicing over 10,000 lacrosse coaches throughout the United States.

Feffie Barnhill has been elected to the Virginia, Delaware and US Lacrosse Halls of Fame as well as receiving the IWLCA Women's College coach's top award. Her alma mater, Ursinus College has honored her with selection to their Athletic Hall of Fame and as a Distinguished Alumnea.

Feffie is currently coaching at Tower Hill High School in Wilmington, De and has assisted this team to 5 Delaware State Championships. She also conducts private lacrosse lessons in the Delaware and Pennsylvania area.