He has also coached in several capacities at the college level, as head football coach at Menlo College, wide receivers coach at Stanford and the University of Hawaii, and through the 2009 season as an assistant coach for San Jose State University. Margerum also served as offensive coordinator for the Scottish Claymores in NFL Europe.
Margerum attended Fountain Valley High School and Stanford University, where he played for the Stanford Cardinal football team from 1977 to 1980. A consensus first-team All-American wide receiver in 1979 and 1980, Margerum was known for his acrobatic catches and sure hands. Margerum was a favorite target of Stanford quarterback John Elway. He held the Pac-10 record for career touchdowns with 32 until 2006 when Dwayne Jarrett broke it and held the Stanford record for receiving yards (2,430) until that mark was broken in 1999 by Troy Walters.
On April 30, 2009, The National Football Foundation & College Football Hall of Fame announced that Margerum was one of sixteen players and two coaches selected to the 2009 Class of the College Hall of Fame.
Margerum was a third round draft choice of the Chicago Bears in the 1981 NFL Draft and earned first team All-Rookie honors that year.  He was a member of the Bears victorious Super Bowl XX team. Margerum served primarily as a third-down receiver and special teams player for the Bears that year, after successfully recuperating from a torn ACL suffered the prior season. Sports Illustrated published a small article (with photo) on Margerum, detailing his use of unorthodox activities - wind surfing and mountain biking - as he rehabbed his knee. During his time with the Bears, critics of Margerum, including then Offensive CoordinatorGreg Landry, suggested he often "left his feet" after catching the ball and had limited run-after-the catch ability after returning from his knee injury. Margerum was also closely associated with his friend and fellow Bears teammate Jim McMahon. After a regular season touchdown from McMahon to Margerum, the two players celebrated by oddly wiggling and shaking their arms at one another while butting heads. Margerum was also known to wear "floppy" black high top cleats as a means to deceive defensive backs into thinking he was slow. After five years with the Bears, Margerum finished up the 1986 and 1987 seasons with the San Francisco 49ers. He later went to camp with the Green Bay Packers, but did not play in any regular season games for the club.