What two-part Grey's Anatomy episode served as the backdoor pilot for Private Practice?

The two-part Grey's Anatomy episode “The Other Side of This Life” served as the backdoor pilot for Private Practice.

The story appeared during Grey's Anatomy season 3 as episodes 22 and 23, introducing the Santa Monica medical practice that would become the setting for the spin-off. Addison Montgomery, played by Kate Walsh, travels to California and meets the doctors and staff of the Oceanside Wellness Group, including Naomi Bennett, Sam Bennett, Pete Wilder, and Violet Turner.

A backdoor pilot is an episode of an established series designed to introduce a potential spin-off through its existing audience. ABC used this Grey's Anatomy storyline to test the characters and premise before Private Practice premiered as a separate series on September 26, 2007. It became the first Grey's Anatomy spin-off, years before Station 19.

The title can cause confusion because the Grey's Anatomy episodes and the eventual Private Practice premiere are sometimes listed together in crossover guides. “The Other Side of This Life” is the backdoor pilot title; “In Which We Meet Addison, a Nice Girl From Somewhere Else” is the title of Private Practice's formal series premiere.