The Three Act Screenplay is the most used structural model in commercial cinema because it is a perfect fit for the arc of the Classic Story (see Story Structure). It is also well suited to stories with an underlying theme of "redemption" – characteristic of many American films.

The Three Act format is characterised by a line of rising action:
In the First Act  a goal or objective is set up for the Protagonist.
The Second Act  features developing opp-osition to that objective.
In the Third Act  a crisis is precipitated and the major conflict is resolved.

Each act rises to a point of climax which throws the story in a new direction. (This major "turning point" in the plot is often simultane-ously a "reversal" of fortune for the Protagonist.) The next act begins with a brief respite before building to an even greater climax than before.

The First Act

The First Act normally takes a quarter of the available time (ie half an hour of a two hour film). It performs a number of crucial tasks in the telling of the story:

In Act One a premise is set up, posing an "active question" which is answered in the final act. (ie. What happens if . . . ?)

An event occurs (the Inciting Incident ) which sets the story in motion. Typically it is some-thing that upsets the balance of the Protagonistês life causing him or her to go into action. This event should lead in an inevitable ® but surprising ® way to the Resolution in Act Three.

The crisis/climax of Act One is generally also the first major point of no return for the Protagonist; a one way gate, committing him or her to the story. Often it appears to offer a solution to the central characterês dilemma which turns out to be false.

The Second Act

The Second Act is the longest, generally using half the available time (ie. an hour from two hours). Act Two builds on the consequences of the direction taken at the end of Act One; adding further complications and conflict.

Sometimes the audience is ahead of the Protagonist in anticipating the consequences of his course of action. Tension is created as they wait for the Protagonist to "catch up". When the Protagonist is forced to face the implications of the "false solution" offered at the end of Act One, it is the audience's strongest point of identification with him/her. Generally this leads to a moment of insight for the character and a new direction in Act Three.

The Third Act

The Third Act uses a quarter of the available time (ie. half an hour from two hours)

In a typical format, the insight gained by the Protagonist at the climax of Act Two resolves his or her Inner Conflict, leading to a clarity of purpose, and allowing the External Conflict to be played out in escalating action. Often the hero goes through a fundamental change of motivation ® the potential for this change being hinted at earlier.

The Crisis in Act Three is characteristically a major decision taken by the Protagonist under full pressure from the story. Ideally it should go beyond the character's sense of right and wrong: ie. a choice between two irreconcilable goods or the lesser of two evils. If he or she then chooses A by sacrificing B ® a price is paid, a risk taken.

At the Climax, the Deep Meaning of the story is converted into action. (It should be possible to understand the climactic action – ie. a confrontation between Antagonist and Protagonist – without benefit of dialogue.) The Resolution concludes the chain of events begun in Act One and provides an answer to the active question posed by the premise.