He played in their three group matches against the Cook Islands, Wales and Scotland, along with their semi-final against Australia. He scored a try against the Cook Islands. In December 2015, Offerdahl captained the United States in their 2017 World Cup qualifying matches against Jamaica and Canada, scoring a try against Jamaica. On 24 September 2017, Offerdahl was named in the United States' squad for the 2017 World Cup. He was named captain of the side and played in all of their games (against Fiji, Italy and PNG). Mark continues to be an advocate for growing the game in the States. Mark's passion for health and fitness extends from the footy field and his own training to helping others reach their goals to live the healthiest lives they can as a qualified Personal Trainer and Nutritionist. Mark married his yoga teacher wife Jenna Offerdahl in London in 2017.