Script specialist handling only dialogue — separate from the screenwriter. Hollywood often brings them in for rewrites and punches during production.
On set, two different writing roles often meet: one has built the story, one polishes the sentences. The dialogue writer comes into play when the dialogue isn't working—or when it's intended from the start to be by a different hand than the dramaturgy. In English-language cinema, this is an established role; in German-language film, it's usually handled pragmatically, depending on how the production operates.
The classic setup: The screenwriter provides the structure, the scenes, the emotional turning points. A dialogue writer is brought in—often only during pre-production or even during shooting—and focuses purely on the spoken word. This isn't a flaw of the original writer but specialization. Some dialogue writers have an ear for rhythm, tone, humor, and authenticity in a way that doesn't require narrative power. They can take the scene as it stands and bring it to life with better lines. This happens constantly on set: an actor can't deliver the dialogue as it's written on paper—too long, too literary, not enough room to breathe. The dialogue writer then sits nearby, notes variations, and tries out new versions with the performer on the same day.
Especially in comedy, the separation of construction and dialogue is evident. You can have a perfectly constructed scene, but if the joke doesn't land or the timing is off, you need someone who crafts dialogue like a craftsman—word for word. In dramatic films, it's more subtle: here, it's about the authenticity of everyday speech, dialect, what characters would actually say, not what sounds literary. A good dialogue writer knows the conversations on the street, in the office, in the family—and transfers that to the screen without making it artificial.
The practice varies greatly. Some productions hire a dialogue writer only for specific scenes or for the shoot—constantly present, making quick adjustments. Others integrate them earlier, already in the screenwriting phase. The dialogue writer works closely with the director and actors, sometimes without their own credit, sometimes with it. Revisions can still be made during editing and post-production, but the cleanest possible raw version from set saves a lot of work afterward. The dialogue writer, therefore, is not the author of the story but the one who ensures the story comes out of the characters' mouths in the right words.