They're rarely spotted without the other by their side.
So it's no wonder Mary-Kate and Ashley Olsen both served as bridesmaids for their friend's wedding in New Zealand last week.
The 30-year-old actresses-turned-fashion designers matched looks in chic all-black gowns, according to Daily Mail.
The former Full House stars locked arms as they walked down the aisle in front of Maggie Kayne and Travis Hayden's closest friends and family.
Mary-Kate carried an oil-paper umbrella to shade the sun, while Ashley held a beautiful bouquet of white flowers.
As she carried the light umbrella, her golden tresses gently blew in the breeze and cascaded past her shoulders.
Mary-Kate also kept with her signature hippie chic style and rounded out her look with several colourful beaded bracelets and vintage earrings.
Ashley swept her blonde locks back into a low bun and opted for a dramatic smokey eye with rosy blush and mauve glossy lip.
Maggie looked stunning in a white rhinestone encrusted kimono-style gown as she shared her vows with Travis.
Meanwhile Mary-Kate, along with her husband Olivier Sarkozy, 47, and Ashley with boyfriend Richard Sachs, 58, enjoyed a bit of leisure time while in Mangawhai, New Zealand.
The group spent four days at the exclusive Tara Iti golf club owned by Maggie Kayne's billionaire father Ric Kayne.
The blonde beauties went boho chic in aviator shades, relaxed-fitting tees and light wash denims.