While the studio insisted the film's running time could not exceed 150 minutes, Lonergan's preferred version was closer to three hours. Martin Scorsese and Thelma Schoonmaker contributed to editing a 165-minute version that Lonergan approved; the cut was never completed due to a budget shortage of $500,000. Eventually, Fox Searchlight Pictures released the 150-minute film in a limited release in the United States on September 30, 2011, to moderately positive reviews from critics. Some considered it overlong, but it was praised for its acting and later appeared in several publications' lists of the year's best films.
Lonergan completed a three-hour extended version incorporating extra footage with revised score and sound mix, which was released on DVD in July 2012.
The film's title is drawn from Gerard Manley Hopkins' poem "Spring and Fall: to a young child", which is discussed in Lisa's English class.
A 17-year-old Manhattan student, Lisa Cohen, shopping on the Upper West Side, interacts with bus driver Gerald Maretti as she runs alongside his moving bus; he allows himself to become distracted, leading to a fatal accident by missing a red light, in which a pedestrian, Monica Patterson, is hit by the bus and subsequently dies in Lisa's arms. Initially, Lisa reports to the police that the driver had a green traffic signal, but later, out of remorse, changes her story. She confronts Maretti, who first pretends to have forgotten the details of the accident, and then reveals to her in anger that he does remember them, but believes he did nothing wrong, causing Lisa to pursue his firing from the company with passion. In collaboration with Monica's best friend, Emily, and cousin, Abigail, Lisa ultimately becomes involved in a wrongful death lawsuit against the Metropolitan Transit Authority, seeking the dismissal of the driver (who is revealed to have caused two previous accidents), as well as monetary damages, which would be awarded to the victim's next of kin, her cousin. Meanwhile, Lisa's life takes various turns, including a flirtation with her math teacher, Aaron Caije, her decision to lose her virginity to a classmate, Paul Hirsch, and various vehement debates with classmates about politics and terrorism.
Lisa and her actress mother have a rocky relationship, with sporadic fighting and Lisa expressing ambivalence toward her mother's boyfriend Ramon. An after-show dinner, attended by Lisa, her mother, Emily and Ramon, ends with Ramon making a remark perceived as anti-Semitic toward Emily. Ramon dies of a heart attack not long after. Lisa has sex with Caije, then later confronts Caije, telling him, in the presence of another teacher, that she has had an abortion. She expresses doubt about who the father was and mentions that there are several possibilities.
The lawsuit reaches a conclusion, with an award of $350,000, but the MTA refuses to fire Maretti, out of concern that it would inflame a labor dispute. Abigail claims the settlement offer, revealing the monetary settlement to have been her primary motivation; this causes Lisa to become very upset and disillusioned with the outcome of the case.
Lisa and her mother plan to attend an opera that Ramon and she were to see before his death. On the way, Lisa sees Maretti driving the same bus that had killed the pedestrian and there is a brief moment where the two see each other. During the opera performance, Lisa's accumulated emotion from the sequence of events bursts out and she and her mother affectionately reconnect, crying together and holding each other as the opera goes on.Anna Paquin as Lisa Cohen
J. Smith-Cameron as Joan Cohen
Mark Ruffalo as Gerald Maretti
Jeannie Berlin as Emily Smith
Jean Reno as Ramon Cameron
John Gallagher Jr. as Darren Rodifer
Allison Janney as Monica Patterson
Kieran Culkin as Paul Hirsch
Matt Damon as Aaron Caije
Rosemarie DeWitt as Margaret Maretti
Matthew Broderick as John Andrew Van Tassel
Olivia Thirlby as Monica Sloane
Kenneth Lonergan as Karl
Filmed in 2005, the film's lengthy post-production sparked multiple lawsuits, which were scheduled to be tried in 2009.
In July 2010, Fox Searchlight stated that Lonergan finally completed work on the film, and that it would be released in 2011.
Margaret received mostly positive reviews from critics and has "certified fresh" score of 75% on Rotten Tomatoes based on 91 reviews with an average rating of 7.1 out of 10. The critical consensus states, "A surfeit of ideas contributes to Margaret's excessive run time, but Anna Paquin does a admirable job of guiding viewers through emotional hell." The film also holds a score of 61 out of 100 on Metacritic (based on 27 critics), indicating "generally favorable reviews."
For her role as Lisa Cohen, Paquin shared the 2011 Best Actress Award from the London Film Critics Circle and received a nomination for Best Actress from the Chicago Film Critics Association. She placed first in critics’ polls from the LA Weekly, the Village Voice, and the International Cinephile Society. On December 23, 2011, Fox Searchlight sent screeners of the film to AMPAS members.
Some view Margaret as a masterpiece. It earned five-star reviews from Time Out, The Daily Telegraph, and The Guardian. It also ranked 31st in a 2016 BBC poll of the 21st century's greatest films.
Despite being well received critically, Margaret was commercially unsuccessful. The film was given a limited release in North America in 14 theaters and earned $46,495. In the UK, it débuted on only one screen in one cinema – Odeon Panton Street in London. Such was the interest in the film that it took £4,595 in its opening weekend, giving it by some margin the highest screen average of any film on release at the time. In France, it débuted on only one screen in one cinema – Publicis Champs Elysées in Paris The worldwide total for the film was $623,292, well below its $14 million production budget.
An extended cut of the film was released on DVD in July 2012 in both the UK and the US. The US release also includes a Blu-ray of the film featuring the theatrical cut in high definition. The Canadian release uses identical packaging and claims to include both cuts but, in actuality, includes only the theatrical cut twice.
Original music was composed by Nico Muhly with additional cues by Elliott Carter. The film also features two scenes at the Metropolitan Opera, featuring "Casta diva" from Bellini's Norma, and "Belle nuit, ô nuit d'amour" (Barcarolle) from Jacques Offenbach's Les contes d'Hoffmann.