Massengale made her international debut at the 2009 FIBA Americas Under-16 Championship in Mexico. She would then go on to represent the USA at both the 2010 FIBA Under-17 World Cup and the 2011 FIBA Under-19 World Cup, taking home the gold on both occasions. At the Under-19 World Cup, she earned a spot on the All-Tournament Team, alongside teammate Breanna Stewart.