[4][2] As a 16-year-old high school swimmer, Kinsella was the silver medalist in the men's 1,500-meter freestyle at the 1968 Summer Olympics in Mexico City, finishing second to U.S. teammate Mike Burton.

At the 1972 Summer Olympics in Munich, Germany, Kinsella won a gold medal as a member of the winning U.S. team in the men's 4×200-meter freestyle relay.

The first-place team of Kinsella, Fred Tyler, Steve Genter, and Mark Spitz set a new world-record time of 7:35.78 in the event final.

John Murphy, a fellow 1972 Olympic Gold medalist, also swam for both Hinsdale Central High School, and Indiana University with Kinsella.

[2] In 1970, while still a high school senior swimming for Hinsdale Central High School and the Hinsdale McDonald's Swim Club under coach Don Watson, he was awarded the Amateur Athletic Union's James E. Sullivan Award in recognition of the outstanding American amateur athlete of the year.