Yes you do.

Right now you may be able to travel to Mexico w/out apassport but I believe in January 2008 you need a passport, even if you are driving across

Mexico doesn’t require you to show your passport, but the USA customs officer will ask you for it when you return.
You’ll need to have one whe you travel by air beginning January 2008, and by land, you’ll need it beginning on June 2008.

Not yet but you will this summer to come back into the USA. I have no idea what they will do to people that slip into Mexico without a passport as they don’t even check sometimes. especially if you are going by bus your documents don’t get checked very throughly. They are going to be on the Mexico side with no Passport and the USA requiring them to show it to get in. I’m sure there will be even more of a grace period or something as this was supposed to have gone into effect Jan 2007

no you dont if you are a us resident you just need your green card and your mexican passaport (if your mexican) or matricula….. if your a us citizen you need a us passaport

If you are an American citizen OR an american green card holder, you do need a passport if you FLY to and from Mexico. You do NOT need a passport to travel to and from Mexico by LAND or SEA until after SUMMER 2008. See website below and read top half of page carefully for current info. Always carry your grren card. After next summer, you will also need to carry your passport from your home country. You may certinly carry it now too when traveling by land…never hurts to have it with you.

Yes, you do.