Slug Line

A slug line, also called a scene heading, is the bold, capitalized line at the start of each scene in a screenplay that orients the reader to where and when the action takes place. It follows a strict three-part format: first, whether the scene is interior (INT.) or exterior (EXT.); second, the specific location; and third, the time of day (typically DAY or NIGHT, though variations like DAWN, DUSK, CONTINUOUS, and LATER are common). For example, "INT. DETECTIVE'S OFFICE - NIGHT" immediately tells the director, cinematographer, and production team everything they need to know about the scene's physical context. The slug line is not merely a formatting convention; it is the screenwriter's first tool for establishing atmosphere, because the choice between an interior and an exterior, a kitchen and a rooftop, day and night, shapes the audience's experience before a single word of dialogue is spoken.

Slug lines carry more storytelling weight than their utilitarian appearance suggests. In No Country for Old Men, the Coen Brothers' screenplay uses sparse slug lines that cycle relentlessly between desolate exteriors and claustrophobic interiors, reinforcing the film's themes of pursuit and entrapment. Aaron Sorkin's scripts for The Social Network employ slug lines to manage the film's complex structure, cutting between deposition rooms and flashback locations with a rhythm that mirrors the narrative's layered timeline. In television, slug lines serve an additional practical function: they help production managers break the script into shooting schedules, grouping scenes by location to maximize efficiency. A slug line reading "INT. HOSPITAL CORRIDOR - CONTINUOUS" tells the crew that the camera should follow the action seamlessly from the previous scene without a time cut.

When writing slug lines, clarity and consistency are paramount. Use the same location name every time a scene returns to a particular place; switching between "INT. JOHN'S APARTMENT" and "INT. JOHN'S LIVING ROOM" creates confusion about whether these are the same set. If a scene moves from inside to outside within a single continuous action, use "INT./EXT." to indicate the transition. Keep slug lines concise but specific enough to distinguish between similar locations. Avoid embedding narrative information in the slug line itself; the action lines that follow are where you paint the picture. Study the formatting guides published by studios and fellowships, as proper slug line format is one of the first things readers check when evaluating a script's professionalism. A screenplay with sloppy scene headings signals an amateur before the story even begins.