Kate Middleton and Prince William met with Norway's Prince and Princess at Windsor Castle.
Princess Mette-Marit wore a bright red gown, while Prince Haakon wore a light blue suit with a blue-and-white polka dot tie.
They all sat down with three leading Norwegian companies to brainstorm potential environmental projects.
Prince William is deeply committed to environmental issues, as evidenced by his establishment of the Earthshot Prize.
The Earthshot Prize aims to recognise and fund individuals who are working to save the planet.
The gathering gathered a lot of royal star power in one picture.