co-signing a mortage...what are the pitfalls?

As a cosigner, you are liable for payments until the loan is paid in full.  Though you're only a cosigner, any later payments on the loan will be reported to credit bureaus and appear on your credit report. Being a cosigner could affect your ability to obtain loans in the future, as the monthly payment is calculated in your debt ratio. As we've seen through the forums, cosigning can bring about complete dissolution of relationships.  I can't begin to cite how many times I've read that so-and-so "ruined my credit" by being late on payments, and the litany of difficulties goes on and on. The one thing to always remember when cosigning is that the debt is 100% your obligation; a lender does not have to request payment only from the primary borrower but can expect you to make payments.