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Does Mark Harmon Know Sign Language?

“It’s a lot easier to do good work when you have good words to say and work with good people,” said Mark Harmon. However, on NCIS, some of his work involves no words. Fans point out that in the show, you can see Mark Harmon use sign language with actress Pauley Perrette.

Does Mark Harmon actually know sign language?

Acting Requires On and Off Screen Skills

It is not uncommon for actors to learn a skill to master a role. Many actors are multi-talented to bring an aspect of real-life to the screen. Harmon has shown the ability to learn new skills for a role. And in this case, it is not just acting. Mark Harmon does know basic sign language.

And his coworker Pauley Perrette, who plays Abby Sciuto, also is familiar with sign language because her mother was deaf. So, the signing in NCIS is based on real sign language.

When Harmon Learned Sign Language

Prior to NCIS, Harmon appeared in a police drama show called Reasonable Doubts. In 1991, Harmon worked with actress Marlee Matlin, who is deaf. In order to communicate on-screen and off-screen with Matlin, Harmon had to learn how to sign with The Sign Company. Unfortunately, the show only lasted two seasons. But it was enough for the signing skills to stick with Harmon which he now occasionally uses with Perrette on NICS.

How well does Harmon sign?

According to some native ASL speakers, Harmon’s sign language as Gibbs in NCIS is at a novice level ASL speaker. Harmon lacks a full vocabulary and grammar in sign language. He also does not incorporate ASL appropriate facial expressions with his signs, and neither does Perrette playing Abby.

Native ASL speakers can tell that Harmon and Perrette don’t need to sign to each other and aren’t completely fluent.

Harmon and Perrette do not sign every word they are trying to convey, which is fine for hearing audiences to get the gist but for deaf audiences it leaves sentences incomplete. Spoken dialogue is being used to flush out what is being signed, so you could not get the full understanding from just watching Harmon and Perrette sign.

Mark Harmon is able to use sign language in what one fluent ASL speaker calls EHCS, or extremely hearing contact signing. Harmon can use a few signs but to native ASL speakers, it appears stiff and doesn’t flow as well as fluent ASL speakers.

Fans say that the signing in Reasonable Doubts was better than in NCIS because at least Marlee Martin was really deaf so she had to rely on signing to communicate and could not fill in gaps with hearing or speaking words.

Could Harmon be using a different signing system than ASL?

Sign Language vs Signed English

Signed English is different from sign language. Signed English is a system of using signs and fingerspelling, but it is not its own language. Mark Harmon’s character Gibbs does not do signed English because he does not sign every word. However, it’s not quite fluent ASL either because he lacks the expressions that native ASL speakers use and leaves out many words when he signs.

Harmon’s sign language is interpretable, but not perfect. Fans need to hear what the characters are saying in the context of the scene to help them understand his signs because he doesn’t sign every word. But some of his simpler signs, when understood, add meaning to the scenes of NCIS.

Examples of Mark Harmon Signing in NCIS

Both Harmon and his costar Perrette can speak in sign language, but that still does not help most viewers know what they are saying. Here are a few translations of their on-screen conversations in sign language.

In episode 1.03, Seadog, Harmon’s character Gibbs and another character Tony approaches Perrette’s (as character Abby) lab. Abby signs “how are you?” to Gibbs. Gibbs signs back to Abby, “I’m good, and you?”

Tony asks Gibbs what they are doing. Gibbs responds that they are communicating. Tony asks where Abby learned to sign, and she signs back “parents deaf.” Gibbs proceeds to translate Tony’s interview with Abby.

In episode 2.05, The Bone Yard, Abby, Tony and Gibbs are once again in Abby’s lab. While Abby is working on a DNA sample, Gibbs walks over to her and signs on her cheek “smart girl”, which to non-ASL speakers appears as an affectionate gesture. But, according to members of the ASL community signing on another’s face indicates intimacy similar to people whispering in each other’s ears.

Harmon’s character Gibbs can also be seen to fingerspell. In episode 3.18, Bait, Gibbs and Abby are signing but Abby asks for clarification of what Gibbs is saying, so he fingerspells P-U-P-P-E-T to her.


Mark Harmon is a renowned actor who is skilled in not only in acting but also in off-screen skills that help bring his characters to life. Sign language is one of those skills, even if he is not perfectly fluent in using it.

He is not afraid to learn something new for a role. Years after first learning to sign, he can still use his basic sign language today.

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  • A storyteller at heart, Amelia is passionate about crafting stories in various formats because she loves to help people. Her stories have reached people around the world, and social media users for various organizations. She has a degree in communications with a special interest in travel and global business.

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