Williams played at Duke for four seasons. During her last year she averaged 14.5 points, 9.0 rebounds, and 2.5 assists per game. Her assist average was the highest of any center in the country in the Atlantic Coast Conference women's basketball league. She ended her career with 426 total blocks, the ninth highest in NCAA history.
Williams was selected to be a member of the first ever U16 team for USA Basketball. The team competed in the First FIBA Americas U16 Championship For Women held in Mexico City, Mexico in August 2009. She led the team leader in rebounds, with 5.2 per game, and averaged 13.4 points per game, second highest on the team. She tied Breanna Stewart for the most number of blocks per game, recording 7 per game. She helped the team to a 5–0 record and the Gold medal at the competition. The win secured an automatic bid to the 2010 FIBA U17 World Championship. Williams was named the Most Valuable Player in the Championship.
2010 U17 France
Williams continued with the team as it became the U17 team. The team competed in the 2010 FIBA U17 World Championship for Women, held in Rodez & Toulouse, France during July 2010. Williams helped the team win the gold medal and an 8–0 record. She was the leading scorer, averaging 13.5 points per game and hit 61.8% of her shots, highest on the team and second highest among all participants.She led the team in rebounds, averaging 7.6 per game. She recorded 16 blocks, second highest on the team. Williams started strong, recording a double-double in the opening game against France, and again, with 20 points and 14 rebounds in the second game against Russia.
In 2011, Williams was selected to be on the USA basketball U19 team at the U19 World Championship, held in Puerto Montt, Chile.The USA won their first five games, but then came up short, losing to Canada 64–52. They were still qualified for the medal round, and played France in the quarterfinal. The USA was down by as much as 13 points early in the game, but took a lead with just over a minute to go in the game and ended up with the win 70–64. The USA took an early lead in the semi-final against Brazil, and went on to win to qualify for the gold medal game. The final game was against Spain. Williams was one of three USA players with 15 points in the game, along with Stefanie Dolson and Kaleena Mosqueda-Lewis who helped the USA win the gold medal 69–46. Williams averaged 8.9 points per game and 5.0 rebounds per game to help the US to an 8–1 record and the gold medal in the Championship game.
