deciding whether a teenage boy is innocent or guilty of killing his father.  The stage directions explain that the deliberation room contains a conference table, twelve chairs, a water cooler, a few windows, and a few doors.  The stage directions also tell the reader that this play can take place in any city during any time period; therefore, a date or place is not given.

Playwright Reginald Rose was inspired to write the play Twelve Angry Men after his own experiences serving on a jury left him fascinated by the procedures and dynamics involved when twelve disparate individuals are forced into a small room and instructed to render a verdict on someone else’s life. A native of New York City, Rose naturally placed his story in that ethnically, culturally, and politically diverse metropolis.

The setting is the New York City Courthouse circa the mid-1950s, and it is summer, a relevant detail revealed by the characters’ comments regarding the weather, as when, right after the jurors are led into the small room where they will debate the merits of the prosecutor’s case, Juror 7 laments, “Y' know something? It's hot. You'd think they'd at least air condition the place. I almost dropped dead in court.” Juror 10 similarly comments on the heat when he empathizes with another juror’s cold symptoms: “These hot-weather colds can kill you.”

So, we know that Twelve Angry Men takes place in a large city downtown area—specifically, in a courthouse—and that it is summer. The building obviously lacks adequate ventilation or, hardly unusual for the mid-1950s, suitable air conditioning. Further details regarding the setting are provided by Rose in his instructions for the production crew:

[Fade in on a large bare, unpleasant-looking room. This is the jury room in the county criminal court of a large Eastern city. It is about 4:00 P.M. The room is furnished with a long conference table and a dozen chairs. The walls are bare, drab and badly in need of a fresh coat of paint. Along one wall is a row of windows, which look out on the skyline of the city's financial district. High on another wall is an electric clock. A washroom opens off the jury room. In one corner of the room is a water fountain.]

These details—large urban area, oppressive heat, lack of adequate ventilation, middle of the 1950s (a period of growing racial tensions in America’s inner cities)—all contribute greatly to the atmosphere in which Rose’s jury deliberates the guilt or innocence of the young Hispanic male accused of murder. The heat is an important element, as it adds to the tensions that will permeate the small room once individual temperaments and attitudes towards racial and social justice begin to clash. Intense summer heat is frequently used as a contributing element in plots that involve simmering tensions growing closer to exploding into violence (see, for example, Norman Jewison’s film In the Heat of the Night and Spike Lee’s Do the Right Thing).

The confluence of variables—heat, confined space, personality clashes born of differing perspectives and attitudes—all contribute to the rising tensions as Juror 8 meticulously redirects the other assembled jurors from their initial inclinations to vote “guilty” to that of an acquittal.

The setting is the location and time in which the story takes place. There are a lot of important aspects of the setting of Twelve Angry Men that influence the events.

According to the Penguin Classic edition, the setting is "The jury room of a New York Court of Law, 1957. A very hot summer day."

In order to understand how the setting influences the events, we first need to consider the cultural context of New York City in 1957. At this time, the memory of WWII was still part of the American zeitgeist, and each of the jurors would probably have been directly influenced by the events of the war. America changed a lot because of the two world wars and the Great Depression in between them, so the jurors would have grown up in a society that had a lot of struggles. Therefore some of the jurors are quite arrogant and bigoted, and unlike today, at that time bigotry was somewhat commonplace and accepted. Remember that was before the civil rights movement or the women's liberation movement were really under way. Today, someone who is bigoted might keep his biased opinions to himself, but in the 1950s, bigots were quick to share their stereotypes and feelings of hatred. The climax of the play really occurs when Juror Ten starts exclaiming angrily about "those people," meaning the poor people living in the slums, and the rest of the Jurors silently stand and turn their backs to him, one by one. This shows the audience that all the jurors except Ten have learned to look beyond the surface and put aside their prejudices to discover the truth about the case.

The location of New York City also influences the events. Now York City in the 1950s was a cosmopolitan place with a varied populace, reflected in the varied characteristics of the jurors. We have a juror who is an immigrant, a juror who grew up in the slums, a juror who appears to be wealthy, and a couple of flashy showmen; we have young and old, opinionated and meek jurors. These various personalities and backgrounds among the jurors reflect the population of the city in which the play is set, and make for a lot of differing opinions and experiences, which creates the conflict of the story. For example, Juror Five grew up in a gang neighborhood, and his knowledge of knife fights is the evidence that persuades Juror Seven to agree that the defendant was innocent and make the vote nine to three.

On top of a general acceptance of violence and bigotry, and the varied characters of the jurors coming from New York City, the playwright, Reginald Rose, creates an uncomfortable atmosphere. The action takes place in the jury room which is furnished with a large, beat-up table, several uncomfortable chairs, a water cooler, and a fan. There is a big window looking out over New York City. There is an entrance door on one side of the stage. On the other side of the stage, a door leads to the bathroom. The bathroom is the only location where the jurors can have privacy; most of the time they are stuck together in the jury room in the sweltering heat. The uncomfortable atmosphere created by the stark room, the cramped quarters, and the oppressive heat create the "angry" mood mentioned in the title. In these conditions, the jurors are quick to argue and to lose their tempers with each other.

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