The third season of The O.C. commenced airing in the United States on September 8, 2005, concluded on May 18, 2006, and consisted of 25 episodes. The first ten episodes of season three aired Thursdays at 8:00 p.m. ET in the US on FOX, a terrestrial television network; however, from January 12, 2006 onwards, The O.C. was shifted to a later time of Thursdays at 9:00 p.m. ET.
Following on from season two, the series continues to follow the characters' lives in the wealthy community of Newport Beach, Orange County, California, with the main characters entering their final year of high school. Series creator Josh Schwartz said he wanted to explore the characters moving away as he "didn't want to be one of the shows that stayed in high school too long". He added that "graduating from high school is such a sentimental moment for kids and parents. It's something we knew we wanted to mine and explore." The season revolves around Ryan Atwood's savior complex causing trouble, and Seth Cohen's lies posing problems in his relationship with Summer Roberts. Seth's mother Kirsten attends rehab in an attempt to put her life back together, while her husband Sandy assumes leadership of the Newport Group after Caleb Nichol's death and finds himself the heir-apparent to a legacy of scandal, and Marissa Cooper spirals out of control after her younger sister Kaitlin causes trouble on her return home from boarding school. The season was released on DVD as a seven disc boxed set under the title The O.C.: The Complete Third Season on October 24, 2006 by Warner Bros. Home Video.
Season three was also broadcast outside of the United States. In Canada, the season was simulcast on the terrestrial network CTV Television Network. It was broadcast on Network Ten on Tuesdays at 8:30 p.m. (local time) in Australia, and premiered several months after it did in the US. In New Zealand the season started February 11, 2006 on TV NZ. It premiered in the United Kingdom on January 10, 2006 on the digital terrestrial channel E4, airing Tuesdays at 9:00 p.m. GMT. The episodes were rebroadcast the following week on the analogue Channel 4, E4's parent channel, on Sundays at 1:50 p.m. GMT.
The season was produced by Warner Bros. Television and Wonderland Sound and Vision. The executive producers were series creator Josh Schwartz, McG, a co-founder of Wonderland, and Bob DeLaurentis. Stephanie Savage, the other co-founder of Wonderland, served as co-executive producer, whilst Ian Toynton served as supervising producer. The staff writers were Schwartz, Savage, DeLaurentis, John Stephens, J.J. Philbin and Mike Kelley. The regular directors throughout the season were Toynton, Michael Lange, Michael Fresco, Norman Buckley and Tony Wharmby.
The third season had star billing for seven major roles. Mischa Barton as Marissa, Rachel Bilson as Summer, Adam Brody as Seth, Melinda Clarke as Julie, Peter Gallagher as Sandy, Benjamin McKenzie as Ryan, and Kelly Rowan as Kirsten all returned to the main cast. Former main cast member Alan Dale did not return due to his character, Caleb, dying at the end of the second season, while Tate Donovan, as Jimmy Cooper, returned only in a recurring role, and then only for the first three episodes of the season.
Logan Marshall-Green returned for the season premiere, portraying Trey Atwood, comatosed as a result of the shooting in the second season finale. Additionally Navi Rawat, Samaire Armstrong, Daphne Ashbrook and Nikki Griffin all made brief returns to guest star as Theresa Diaz, Anna Stern, Dawn Atwood, and Jess Sathers, respectively. Willa Holland took over from Shailene Woodley in portraying Marissa's younger sister Kaitlin, who returns to the show after being away at boarding school last year. Cast member Michael Nouri continued as Summer's dad, Dr. Neil Roberts, who became a larger part of the series. Other actors to leave the series were Nicholas Gonzalez (D.J.), Michael Cassidy (Zach), Shannon Lucio (Lindsay), Olivia Wilde (Alex), Billy Campbell (Carter), Kim Delaney (Rebecca), Johnny Messner (Lance), Kathleen York (Renee), and Marguerite Moreau (Reed).
The season introduced a number of new students to the show. Additions to the cast included Autumn Reeser, Cam Gigandet, Ryan Donowho and Johnny Lewis, as new social chair Taylor Townsend, rival surfers Kevin Volchok and Johnny Harper, and Johnny's best friend Chili. Jeri Ryan and Jeff Hephner also joined the cast to portray new adult characters Charlotte Morgan, a mysterious woman Kristen befriends in rehab, and Matt Ramsey, an overzealous business partner working at the Newport Group. New guest stars in recurring roles included Paula Trickey as Taylor's mother, Veronica Townsend; Erin Foster as a Newport Union student called Heather; Kayla Ewell and Nikki Reed as Johnny's girlfriend, Casey, and cousin Sadie; Eric Mabius as new Dean of Discipline, Jack Hess; Shaun Duke as Henry Griffin, head of the board at Newport Hospital; and Morena Baccarin as Griffin's daughter Maya. This is the final season for original cast member Mischa Barton who played Marissa Cooper; Marissa tragically dies in a car accident in the season finale.
Season three was widely regarded by both fans and critics as the worst season of The O.C. The season premiere attracted 7.5 million viewers, but average viewing figures decreased twenty percent from the previous season to 5.6 million. The first half of the season averaged 6.3 million viewers, representing a substantial decrease in the show's popularity. However Marcy Ross, head of current programming at FOX said that the "ratings are perfectly fine and acceptable". After the eventual cancellation of the show, Schwartz admitted that "the whole first half of the third season was a total mess".
The third season was nominated for five Teen Choice Awards and won four of them, including "Choice Drama/Action Adventure Show" and "Choice Actor: Drama/Action Adventure", which Adam Brody won for the third consecutive year. IGN faulted a season which, in their opinion, had "far too much time and too many episodes spent with the less than beloved character Johnny". IGN also noted that "Kirsten and Sandy both suffered from unsatisfying stories", and that the departure of character Caleb Nichol had been a mistake "as he had been a great character to bounce off both of the elder Cohens". In September 2007, Schwartz admitted in an interview for New York that the show "went down the wrong road" with Johnny. The season did, however, receive some praise. The new character Taylor Townsend was stated as being "played to perfection by Autumn Reeser" and her character was described as "one of the greatest elements of The O.C." Jeffrey Robinson of DVD Talk described the storylines as "very intelligent and also incorporate a great deal of humor to keep your interest".
USA Today critic Robert Bianco said that the season premiere was "as dreary and ridiculous as any episode the show ever gave us", but the season finale was commended by IGN's Eric Goldman for killing off main character Marissa Cooper. Goldman said that "the episode documenting her demise was a fairly strong one" and that the following season "would really pay off this shocking twist". Despite not being the final season it was also noted that the graduation of characters gave "the show a feeling of ending".