Co-signed Tenants or a Single Lessee?

[Jay Staudt]

I had someone respond to my rental ad saying that she would like to look at the property and would be moving in with her boyfriend. I started wondering about a few things and I'm hoping some more experienced landlords here can offer some advice: in a situation with an unmarried couple, what are the pros and cons of having one person sign the lease alone, vs. having them co-sign together? Am I allowed to state my preference to the potential tenant, or is this a decision that needs to be made on their end?