'Modern colourful clothes' is correct. When we're describing things, their age comes before their colour. The order of adjectives (describing words) is this: 1) Opinion 2) Size 3) Age 4) Shape 5) Colour 6) Origin 7) Material 8) Use So, for example, this sentence demonstrates the order of adjectives: I saw some dreadful big old round brown French wooden dining tables. dreadful = opinion big = size old = age round = shape brown = colour French = origin Wooden = material Dining = use

In reality the order of adjectives in English is more flexible than the rule outlined by Sarah (though this is a good general guide). However the mistake Sarah is making is to equate the adjective, "colourful", with actual colours like blue, red etc. You would definitely say, "modern blue clothes" but "colourful" is not a colour, it can just as much be an opinion and I wouldn't hesitate to say, "colourful modern clothes."