What type of clothes would I take to Canada in May 2011?

Summer clothes, because some places could be very warm or hot, but bring at least one pair of jeans and some things you can layer because it may be cool in the mountains after the sun is down. Cardigan and waterproof jacket plus a shirt and fleece vest should get you through the coldest evenings you're likely to encounter. Shoes you can walk in, like runners or light hiking boots..