Clark attended Dowling Catholic High School in her hometown of West Des Moines, Iowa, where she was named a McDonald's All-American and rated the fourth-best player in her class by ESPN. In her freshman season with Iowa, she led the NCAA Division I in scoring and earned All-American honors. As a sophomore, Clark was a unanimous first-team All-American and became the first women's player to lead Division I in points and assists in a single season. In her junior season, she was the national player of the year and led Iowa to its first national championship game. Clark again led Division I in assists and set Big Ten single-season marks in points and assists. As a senior, she repeated as national player of the year and helped Iowa return to the national title game. Clark became the women's Division I career and single-season leader in points and three-pointers and broke the all-time conference record in assists, while leading the nation in both points and assists.