Make sure that both switches are three-way switches with three screws plus a ground screw each. Then wire the switches as shown in the diagram.

There are multiple ways to wire a three way switch circuit, depending on whether the light is "between" the two switches or on the end past one of the switches. There are plenty of diagrams out there that explain the possible wiring solutions, but its easy to pick the wrong one if you don't know the exact wiring layout.

Bruce

Thank you all for your replies. Thankfully, I'm still covered by the builder's warranty and would rather not do this on my own.