In the summer of 1968 Ćosić was in a European team with Finnish player Veikko Vainio. Vainio, a student at Brigham Young University, told him about life in college and invited him to play for BYU. Ćosić accepted this invitation and moved to the United States in 1969.[6] In his freshman year he played 12 games, averaging 17.4 points and 12.6 rebounds per game. In his sophomore year he averaged 15 points and 8.4 rebounds per game, leading BYU to the 1971 WAC Championship.