Mary-Kate and Ashley Olsen spent their 13th birthday on the set of their hit video series, Two of a Kind , in matching red and pink printed tops and blonde bobs.
In addition to their TV programmes, videos and films, the teenage twins had a clothing line at Wal-Mart claimed to be the leading US label. Note this matchy-matchy black suit moment.
In 2004, the duo began to rebel against their matching style ways and wore different looks while promoting their film New York Minute . Mary-Kate went as far as dying her hair brown.
It was in 2006 that the pair really began to earn their fashion stripes by bagging an invite to the star-studded Met Gala Ball - the fashion world's equivalent to the Oscars. Both of the sisters opted for long-sleeved gowns.
At the tender age of 19, the girls were already red carpet regulars, clocking up yet another Met Ball invite in 2007.
Black quickly became an Olsen wardrobe staple as the actresses reached their early twenties and both returned to their signature, wavy-blonde hair.
Mary-Kate was embracing her hippy-chic style by wearing a drop-waisted Missoni dress to a charity gala in New York...
...While Ashley wore an orange vintage gown with leaf embroidery to the 2009 CFDA awards. It was one of the few times the twins were pictures 'alone' on the red carpet.
Reunited once again, eclectic fashion was on the cards for the Olsen girls at the MOMA film benefit in 2009. Ashley (left) was wearing her favourite Manolo Blahnik heels, made famous by the Sex and the City series.
Ashley Olsen left behind her 'butter wouldn't melt' days when she opted for white lace and vampy make-up on the red carpet.
The sloppy, oversized look has become an Olsen trademark in recent years, with both twins opting for slouchy clothes in a muted palette.
At the 2011 Met Gala Mary-Kate wore a red vintage Givenchy couture dress...
...while her twin chose a glamorous vintage Christian Dior gown with puff sleeves and a thigh-high split.
Chanel couture was the order of the day for the Olsen girls while also showcasing bags from their own fashion label, The Row.
On the red-carpet the twins try to outfox the paparazzi with their matching hairstyles and glasses.
A pro at the 'I just threw this together' look, Mary-Kate sports a striking red trouser suit while out and about in New York.
While Mary-Kate champions the androgynous, double-denim look (not an easy one to pull off!), her twin channelled a ladylike demeanour with a full skirt and simple white shirt.