What is the three-act structure?

The three-act structure is a model for dividing a story into three parts: a setup that introduces the characters and their situation, a confrontation in which they pursue something against mounting obstacles, and a resolution in which that struggle is settled. Two turning points, called plot points, move the story from the first act into the second and from the second into the third. Screenwriting teacher Syd Field made the model standard in his 1979 book Screenplay, where a two-hour film runs roughly 30, 60 and 30 minutes, a 1:2:1 proportion (David Bordwell). It is often traced to Aristotle, who in fact described only a beginning, a middle and an end; the three-act play comes from later theatre, most clearly Lope de Vega's advice of 1609. Film scholars such as Kristin Thompson argue that most Hollywood films actually fall into four parts. In short forms the same shape compresses into minutes or seconds, and movie trailers usually leave the resolution out.

What happens in each act of the three-act structure?

Each act has one job, and each plot point changes the direction of the story. Syd Field's own paradigm worksheet labels the acts Set-Up, Confrontation and Resolution and places them on a 120-page script, on the common assumption that one page equals about one minute of screen time (Syd Field, The Paradigm Worksheet).

Field defines a plot point as any incident that "hooks into the action" and turns it in another direction, and he counts the beginning, the two plot points and the ending as the four elements of structure (sydfield.com). The acts describe the order of dramatic functions. Field writes that a story has a beginning, middle and end "not necessarily in that order", which leaves room for flashbacks and non-linear films. The page numbers are guides. Bordwell notes that readers of Screenplay went looking for plot points at roughly 25 and 90 minutes of running time.

Did Aristotle invent the three-act structure?

No. Aristotle's Poetics (4th century BCE) says a complete action needs a beginning, a middle and an end, but it never divides a drama into three acts. In chapter 7 he writes that "A whole is that which has a beginning, a middle, and an end", and he defines each by causality: a beginning follows nothing by necessity, an end has nothing after it, and a middle comes between (Poetics, trans. S. H. Butcher). When he does divide a tragedy, in chapter 18, he splits it into two parts, a Complication and an Unraveling, with the turning point of fortune between them (Poetics, chapters 12 to 20). The sections of a Greek tragedy that he names in chapter 12 are the prologue, the episodes between choral songs, the choral songs themselves and the exode. Bordwell points out that Aristotle does not mention act divisions because Greek plays did not have them (Bordwell).

Acts came later, and the number changed with the period:

Lope de Vega is the closest ancestor of the modern model. He credits the dramatist Cristóbal de Virués with reducing comedy to three acts from four, and his description of each act anticipates setup, complication and a withheld outcome. Bordwell calls modern three-act advocates heirs of a "Lope-Hegel tradition" and says that where Hollywood itself picked up the idea "is still hard to say". Field's contribution was to make three acts, two plot points and a page count the default vocabulary of screenwriting.

What are the main criticisms of the three-act structure?

The main criticism is that the model does not describe how most films are actually built. Kristin Thompson, whose book Storytelling in the New Hollywood (1999) analyzes the structure of Hollywood films, found that they tend to fall into four large parts of roughly equal length, each about 25 to 35 minutes, so a two-hour film has four and a 2.5-hour film tends to have five (Kristin Thompson, "Times go by turns"). She names the parts the setup, the complicating action, the development and the climax, usually followed by a short epilogue (David Bordwell, "Anatomy of the Action Picture").

Seen through that lens, Field's second act is two parts joined at the midpoint. Bordwell observes that three-act writers effectively split the second act into two stretches around a midpoint, which is close to Thompson's four-part shape. Thompson also calls Field's definition of the plot point "pretty vague", since almost any event that changes the story's direction can qualify.

A second criticism concerns prescription. Thompson notes that Field declared all films have three acts. She presents her own four parts as a tendency observed in finished films and says films are not required to have it. The habit Bordwell describes of timing films to find plot points at set minutes shows how easily a teaching model becomes a checklist. The third criticism is historical: attaching the model to Aristotle gives it an authority his text does not support, as the section above shows.

How does the three-act structure work in a movie trailer?

A trailer usually keeps the first two acts and withholds the third. Stephen Garrett, co-founder of the trailer house Kinetic, writes that "trailers lend themselves to a three-act structure" and builds a trailer's music from three cues to match (Filmmaker Magazine). In his description, the first act introduces the characters and their world, the second complicates it with obstacles, and the third intensifies the conflict and the excitement. The resolution is exactly what a trailer must not give away: his rule is to "never resolve anything!" He adds that a trailer can also have four acts, or one. A trailer's third act is therefore a climax of tension that ends on the title, where a film's third act would settle the story. The rest of the craft, from trailer houses to test screenings, is in our guide to how movie trailers are made.

yume's two trailer films follow that adaptation at the scale of one person's life. Trailer of Your Life opens in a cinema seat, places the person it stars in two famous movie moments and builds their real career into the plot until one last shot where reality bends. The Legend of You turns the things someone you love cares about into big-screen scenes with them in the lead, while the music builds to one final title; the page's example ends on "The Legend of Maarten, Season 57 begins". Both keep a setup and a rising build, and both put a title card where a resolution would go. Neither adds a setback to fill the confrontation: both are made from the real details the buyer supplies, and a birthday or a career does not need an invented struggle to feel like a film.

Does a short film or ad need three acts?

A short film or ad needs a change the viewer can follow, and three acts are only one way to organize it. Aristotle's own test for length is that a story should be long enough to allow "a change from bad fortune to good, or from good fortune to bad" (Poetics, chapter 7). That test works at any length, which fixed act proportions do less well.

As a calculation, applying Field's 1:2:1 ratio to a 60-second film gives about 15 seconds of setup, 30 of confrontation and 15 of resolution, and to a 10-minute short about 2.5, 5 and 2.5 minutes. The ratio still divides the time, though 15 seconds leaves room for little more than a single image of the situation. Thompson's finding points the same way. If a feature's large parts each last 25 to 35 minutes, then by her measure a short cannot reproduce a feature's rhythm of turns and has fewer turns, placed much closer together.

Research on advertising suggests that a complete dramatic arc still helps in very short forms. Keith Quesenberry and Michael Coolsen analyzed 108 Super Bowl commercials over two years and found that ads following Freytag's five-act dramatic form received higher consumer ratings, and the more acts an ad contained, the more favorably it was rated (Journal of Marketing Theory and Practice, 2014; Johns Hopkins summary). The study measured an association in one advertising showcase and used a five-part model, so it supports story completeness in ads rather than three acts specifically.

Some scholars of the short film question act models altogether. Richard Raskin, a scholar of the short fiction film at Aarhus University, set sequential models that prescribe "a specific path or dramatic curve" against his own approach of balancing five pairs of qualities, such as causality and choice, consistency and surprise, and simplicity and depth (P.O.V., 1998). For a short piece, a useful working rule follows from these sources: set up one situation quickly, let one change develop, and decide deliberately whether to resolve it or, as trailers do, to stop on the peak.