Carpenter competed for Team USA under-18 in an Under-18 three-game exhibition series against Canada's best in Calgary, Alberta. She helped the US team win the 2009 Czech Challenge Cup in Prague. She scored a goal for Team USA in the gold medal game of the 2010 IIHF World Women's Under 18 Championship but the team ultimately fell to Canada and had to settle for the silver medal. She was the youngest girl for Team USA in the tournament at fifteen-years-old. She finished the tournament with eight goals and one assist in five games. She was tied for second in team scoring behind Kendall Coyne.