How can I indicate a dress code for a party?

I am co-hosting an engagement party this September and we are trying to get the wording right for the dress code. Basically we want no runners, no guys in jeans, sort of business casual but not too preppy. If it is nice the party will be held in the back garden. We don't want to use dress to impress as we are afriad people might think it is a little dressier than we want. I know there is a line that bars/clubs use but we can't think of it. Help!

How about casual chic.

Business casual is fine wording- anything else would be too fancy. Clubs around here just say "no sneakers, hats or jeans- but I think that common sense." Also your invite- should be formal on paper, not an evite or a phone call and that tells the person how to dress. You can't send a casual invite if you don't want jeans. I just went to a "fancy" housewarming and the girl was shocked no one brough gifts or dressed up but we were invited via Text message. Now if I got a formal printed invite- I would have know that this is a nice event. Unfortunately, you already know who is going to wear jeans- some people can't be stopped- even if it reads formal. I went to a wedding where I saw a man in a suit with construction boots because he didn't own another pair of shoes. What are you going to do?

You can say: "Dress - Business Casual - no jeans". People will get the message and realize the kind of party it is.