LBF- You were probably listed on the lease as a tenant when you were a kid, not someone who was holding the lease. Having a Co-signer is basically guaranteeing that if you won't/can't pay your rent, he or she will. That is a big responsibility for someone to take on, and most people will not do so lightly-- you can't just ask a stranger to co-sign, in other words. Usually a lessor (someone who is leasing something) will ask for a Co-signer when he is reasonably certain that the signer can pay the debt, but wants an insurance policy that the money contracted for will be received. Hope that helps.