Rachel McAdams stepped out last night for the LA premiere of new movie The Vow, a Valentines-friendly romance which she stars in alongside Channing Tatum.

Tackling one of Spring's hottest trends - pastel colours - she chose a super-fitted, va va voom strapless cocktail dress by Vivienne Westwood for the occasion, teamed with nude Christian Louboutin heels and chain detail jewellery.

The dress features Westwood's trademark corseting in the front, but the real detail is down the back where gathers and a waterfall frill give it some added drama. Pale pastels like mint and Tiffany blue are not the easiest colours to pull off, but McAdams managed to pull it off and looks suitable feminine and romantic, which is fitting for the tear-jerker of a film she's promoting.

Here's the trailer for those who've yet to see it...we are loving the wedding dress!