McLaren attended the University of Pittsburgh, where he was considered one of the greatest all-around athletes that Pitt ever produced. In addition to being a football All-American, he was also a two-year member of the basketball and track teams. McLaren played four varsity seasons as fullback at Pittsburgh from 1915 to 1918. While playing for the Panthers he only lost one game while winning thirty decisions. He was a member of three national championship-winning teams under head coachGlenn "Pop" Warner. In 1916, the Panthers beat several national powers while not giving up a single point. During the next two seasons McLaren won All-America honors. In 1917 season, McLaren helped the Panthers to a 10–0 record. That season, he established single season school records when he scored 13 touchdowns and rushed for 782 yards including a then record 91-yard touchdown against Syracuse University. Pitt's undefeated 1917 team was known as "The Fighting Dentists" because on occasion every position was filled by dental students. The dental students on the 1917 team included McLaren, Katy Easterday, Skip Gougler, "Jake" Stahl, and Jock Sutherland. In 1918, his senior season, he served as Captain of the Panther football team and was also president of his senior class. He still ranks among the University of Pittsburgh all-time leaders in both scoring and rushing. One of McLaren's most noted achievements was that he was never stopped for a loss on a running play.
College coach
McLaren was a college football coach from 1919 to 1929. In 1919, McLaren was named as head football coach at Emporia State University, then known as Kansas State Normal College, in Emporia, Kansas. He got the position based on a recommended by Pop Warner. He became 11th head football coach for Emporia State and held that position for just the 1919 season. His overall coaching record at ESU was 1–5–2. This ranks him 20th at ESU in terms of total wins and 19th at ESU in terms of winning percentage. He next served as the head football coach at Arkansas, where he compiled an 8–5–3 record. As Arkansas head football coach McLaren personally very popular coach but was let go because number of wins did not meet expectations. From 1922 to 1926, he coached at Cincinnati, where he compiled a 16–26–3 record. From 1927 to 1929, he coached at Wyoming, where he compiled a 7–19 record. His overall record as a head coach is 32–55–8.