Hi all, how would this work? I go to U.S. and leave before 90 day period is reached and then return for a further 90 days and so on. Is this legal?

It is legal until they say otherwise.

You cannot simply "step out" to say Canada or Mexico and then immediately try to return and get a new 90 days.... It does not work that way

Exactly... besides I believe it is 90 days in any 12 month period. Someone will correct me if I am wrong

Welcome to vj, good luck to ya!

No its not 90 days in 12 months..... You are admitted for a maximum stay of 90 days then you must leave, but you could come back for another 90 day stay 3 months later.... My parents have used the VWP to visit me 3 times durring 2007, each stay was for 85 days... they had no problems but were told that they must be spending more time n their own country than in the USA in any 12 month period or they could be denied entry based on the fact that they are residing in the USA longer than they are in their home country....

Kez

Yup, I think it is up to 6 months per year but at no more than 90 days at a time.

At the end of the day they can deny entry at any time if they feel you are using the VWP as a means of temporary residency. It's not there to be abused but if you don't mind being potentially turned away when Immigration get a bit annoyed then by all means - give it a go! I know there are people who have gone back and forth like that and managed it for a few times in a row but then were denied entry on like the third or fourth time

Canadians can visit for up to 180 days in a twelve month period. But I don't think someone on the VWP would be able to leave and re-enter a multiple of times, I would think they would be tapped out once they have reached 180 days as well.

Well, it's not really written down anywhere quite like that, but that's a good summation of a way you could visit regularly and still be admitted.

A CBP officer is going to look at it from the standpoint of how much time you are spending in your native country vs. time in the US. And they are the ones with the ultimate authority.

yes it is up to the POE as it does not actually say how many times you can visit
my fiance has been here 3 times since May of 07 on the VWP stayed 3 weeks the first time. 7 weeks the next and 11 weeks the last time...
He has been back home in the UK for almost 2 months now and he is coming tomorrow to Canada so we can vacation together! YAY ( i cannot wait to see him!) We will try to come back here so it will be interesting to see if he can come here for the 4th time... it is technically another year as he has not visited in 2008 yet LOL!!
Wish us luck!

Here's what my fiance was told (I'm in the US, he's in the UK)...

For however long you spend in the US on the visa waiver, you have to spend AT LEAST that amount of time in your home country. For instance, he came and visited for 6 weeks, so he can't came back over on the visa waiver for at least another 6 weeks. I'm assuming that is to prevent people from, say, coming to the US on a waiver for 90 days then going home for a week or two then immediately coming back for another 90 days.

Well, yes you're correct that CBP will be watching for people going home for a week or two and then coming back in. But there really is no hard and fast example like the one you gave.

According to a former member of VJ who used to be a CBP official, the 'rule' would be turnbacks of people who effectively are making a home in the US.

From past observations, I feel visits of a month or less with return stays in the home country of 3 months or more before the next US entry will net the best result.

I think that it totally depends on the mood of the POE operator... BUT I do concur that from all accounts they really will question you and maybe deny you if you are spending more time in the USA than out of it..
My experience of 2007 on the VWP was like this..

Jan 2007 - in the USA for 3 weeks.. left mid February.
March 2007 - returned to the USA and stayed for almost the full 90 days until the end of May
(so I was only back here in Australia for 6 weeks even though I had been in the USA for 14 just beforehand - so it doesn't work for the above theory that you have to be out of the USA for the "gap" to be the same as what you were there)..
Mid July 2007 - returned to the USA and was there for about 76 out of the 90 days leaving at the end of September

I was not questioned any differently at any of those times.
Really they are looking/questioning folks who they believe are trying to buck the system or get around it - if you are doing nothing wrong and are not trying to twist their system, and you have strong ties back in your homeland - the problems should be minimal.

have a GREAT day
Tracy
:-)