After graduating in 1980, Arendsen met Joyce at a softball clinic in Meriden where she impressed Joyce with her pitching skills. Joyce then encouraged her to try out for the Raybestos Brakettes, the top amateur team in the country. She earned a spot on the team and won 95 games in her first four years. She also competed at the national level during the 1981 World Games in Santa Clara, California, where she helped the United States win another first-place finish. Arendsen pitched four shutouts, culminating in a perfect game in the championship final. She returned to the Pan American Games in 1983, where she led the team to a silver medal. While continuing to play amateur softball, she accepted various assistant coaching positions at Temple University, the University of Connecticut, Northwestern University, and Yale University.