Grey's Anatomy and Private Practice Crossovers

Since the 2007-2008 television series, when Private Practice debuted, Crossover Events between both Private Practice and it's parent series Grey's Anatomy have become frequent. The most prolific crossover occured in February 2009 and featured many character from each series crossing over. Because of her involvement in both series', the character of Addison Montgomery is often at the forefront of the crossovers. As of yet, a total of three crossover events have taken place.

May 2008

 * Episodes: "Piece of My Heart"
 * Featured Characters: Addison Montgomery

In May 2008, after the conclusion of the first season of Private Practice, Addison Montgomery returned to Seattle Grace for the first time since her departure for L.A in In Which We Meet Addison, a Nice Girl From Somewhere Else. Addison's brief return allowed her to check up on a patient with a complex condition that eventually required surgery, but also allowed Addison to realize that leaving Seattle For Los Angeles was the right thing to do.

It is commonly speculated that Kate Walsh's appearance as Addison in the fourth season of Grey's Anatomy occured because the Writer's Guild Strike of 2007-2008 ended production of Private Practice after only 9 episode were ordered and produced and, as a comprimise, Walsh was written into an episode of Grey's Anatomy. Because the concept of the "crossover" was not yet fully developed, this episode featured little reference to Private Practice and little reference to the characters and other storylines that weren't relevant to the narrative of Private Practice (such as the storylines between Izzie and Alex) were included.

After the sucsess of the episode "Piece of My Heart", the idea of a large scale crossover between the two shows was created and was something both the creative forces behind the series and the network were keen to produce.

February 2009
Details
 * Episodes: "Beat Your Heart Out", "Acceptance", "Before and After", "Ex-Life", "An Honest Mistake"
 * Featured Characters: Addison Montgomery, Derek Shepherd, Archer Montgomery

The most prolific crossover [PROVIDE DESCRIPTION OF STORYLINE]

Throughout the crossover Kate Walsh (Addison Montgomery), Audra McDonald (Naomi Bennett), Taye Diggs (Sam Bennett), Justin Chambers (Alex Karev), Chandra Wilson (Miranda Bailey), James Pickens Jr. (Richard Webber), Eric Dane (Mark Sloan) and Patrick Dempsey (Derek Shepherd) appear on the opposing series, all of whom recieved a "Special Guest Star" credit.

The rest of the Grey's Anatomy and Private Practice cast (Pompeo, Oh, Heilg, Knight, Ramirez, Leigh and McKidd for Grey's Anatomy and Daly, Adelstein, Strickland, Lowell and Brenneman for Private Practice) all appeared in the episode of their respective series', recieving regular billing.

October 2009
Details
 * Episodes: "Right Here, Right Now"
 * Featured Characters: Addison Montgomery, Miranda Bailey

Coming off the heels of the sucsessful February 2009 crossover, a further crossover was planned for the start of the 2009-2010 television season. This was the first crossover to take a more patient-centered approach as the crossover followed the attempts of Miranda Bailey's patient Sarah to recieve a liver transplant. The crossover began in the Grey's Anatomy episode "Invasion" where Bailey organized a liver transplant for Sarah, only for Izzie Stevens to incorrectly read her chart and give her to the wrong medication making her transplant impossible. Bailey then headed to Los Angeles with Sarah, where her sister and a possible donor, lived and Addison and the Oceanic Wellness Group heloed Bailey find her a transplant while, in Seattle, the ramifications of Izzie's mistake led to her being fired.

In the Private Practice episode "Right Here, Right Now", Addison and Sam became involved in the case which was complicated when Sarah's sister tested HIV positive, making Addie, Sam and Bailey question the ethics of the situation. After twisting the arm of Charlotte, Bailey and Sam perform surgery on Sarah and give her her sister's liver. This crossover allowed Sam to return to surgery (which would become important in the following episode "Pushing the Limits") and also showcased the end of the flirtatious relationship between Sam and Bailey established in "Ex-Life", during the previous crossover.

In regards to this crossover, "Invasion" isn't regarded as part of the cross over.

Crossover Appearances

 * * Appears only in Grey's Anatomy during the crossover
 * ** Appears only in Private Practice during the crossover

As of October 2009, Addison and Bailey are the only two characters to appear prominently in every crossover.