This was Mark Zuckerberg’s leadership moment, and body language experts say the Facebook CEO mostly nailed it.

The 33-year-old billionaire testified before Congress for the first time on Tuesday, fielding fiery questions from 44 senators at a joint session of the Judiciary and Commerce committees about data privacy in the wake of Cambridge Analytica scraping the personal information of 87 million Facebook users, not to mention the alleged Russian interference on the social network that now counts more than 2 billion users.

Zuckerberg, who is notoriously awkward about speaking in public, received a “crash course in humility and charm” with consultants before his four-plus hour testimony streamed live on all of the major news networks and online, the New York Times reported. And career coach Roy Cohen, author of “The Wall Street Professional’s Survival Guide,” told Moneyish that Zuck’s preparation paid off.

“He really is presenting himself as a leader,” Cohen said. “It feels to me like he is being repeatedly chastised by a group of elderly critics in a very authoritarian setting, and he is demonstrating enormous respect, dignity and restraint.” He noted that while some senators posed questions that suggested they weren’t familiar with the scope of what Facebook does (such as Sen. Orrin Hatch asking,“How do you sustain a business model in which users don’t pay for your service?” and Zuckerberg replying,“Senator, we run ads.”), the young tech titan began each response with a polite “Senator” and used the opportunity to educate rather than insult the interviewers.

In fact, Facebook stock rose 4.5% during the regular session Tuesday while Zuckerberg was testifying, to close at $165.04. And it continued ticking up a fraction in after-hours trading as he continued to testify.

Body language expert Patti Wood countered that Zuckerberg showed some signs of anxiety and anger throughout the grilling, particularly in how he set his mouth and looked down at his notes. But she praised his apology for being full of genuine feeling, and noted the gravity he brought to the proceedings, such as dressing in a serious suit in lieu of his usual athleisure attire.

Here’s what you can take away from Zuckerberg’s testimony if you’re ever in the hot seat.

Dress to your audience. Zuckerberg swapped his signature gray hoodie, t-shirt, jeans and sneakers for a neat navy suit and blue tie. He also wore a suit when testifying in a Dallas courtroom to defend Oculus last year. “He is in a setting that is taking itself very seriously, so he has aligned himself with the tone and the mood of that setting,” said Cohen. Notice he didn’t wear a flashy tie; you want to blend in. This is not the place to make a statement with jewelry or accessories. “His company has been seen as delinquent, so he is minimizing the distance between himself and the people who are doing the questioning by dressing professionally like them,” said Cohen. “He doesn’t want to look like he is testing the limits.”

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Come prepared — but don’t read off your notes. Zuckerberg gave interviews to CNN and Vox over the past few weeks that hammered home his main talking points on what Facebook will do to rectify data and security issues, a move that helped him hone his responses to questions on Tuesday. He also reportedly received media coaching to rehearse his answers, as he was composed in fielding every question. But Wood noted his opening statement felt scripted because he was repeatedly looking at his notes. “You’ll note that he looks down quite a bit towards his notes — his notes being something that will give him security, but also looking down a little bit in embarrassment, as well but clearly uncomfortable,” she said. Work to get off book.

Make a sincere apology. Zuckerberg released his apology statement ahead of the hearing, but his delivery came through as genuine rather than scripted because he expressed clear remorse. “I really see and hear a true apology. He says, ‘I’m sorry’ and then he takes full responsibility, even making the statement, ‘I own the company. I am responsible for what happened,’” said Wood. “You can actually hear a break in his voice as he apologizes, and that is very difficult to fake. In fact, I find I can’t coach people to do that! He really did feel pain at what had happened.”

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Give each speaker your undivided attention. Zuckerberg looked at each senator as he or she questioned him, and maintained eye contact while answering. He also looked around the room. “Each senator gets his full attention, but he is also talking to the group, and that is a very powerful move because he is not backing down,” said Cohen. “That’s the sign of an individual who is open and honest. It’s not like his eyes are darting, or he’s looking at the ceiling or the floor, like he has something to hide.”

Compose yourself. Zuckerberg didn’t fidget, which shows control, but Wood noted that he had a habit of ending his answers with a “masking smile” that sometimes slipped into a grimace. “You could see that anxiety in the tension around his mouth; he gives a thin, straight line trying to suppress his anxiety, but the fact that his face is not relaxed, and the lips aren’t turned up at the end slightly … bely his anxiety and fear,” she said. But Cohen praised him for addressing each questioner as “Senator” and keeping his cool. “There is no smirking and no eye-rolling, and so he is coming across with enormous maturity, grace and respect, even when they throw ‘darts’ at him,” he said. “And sometimes the questions were rude or long-winded, but he has been enormously patient with them.”

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Think before you speak. Zuckerberg paused before answering many questions, and often asked for clarification before responding. This not only buys time to get your thoughts together, but can also get someone to rephrase a long-winded question better. “It’s important that he’s not disagreeing — he’s asking for clarification — because you don’t want to establish a conversation that is adversarial or confrontational,” said Cohen. “And his responses all came across as well thought-out because he took a minute instead of diving in.” This also helped him to deflect questions; when asked whether he supported regulating Facebook, he said he would support the “right” regulation, for example. When asked if Facebook user would have to pay to opt out of ads, he carefully answered that, “There will always be a version of Facebook that is free.”

Move to continue the conversation. Several times, Zuckerberg promised to continue the conversation and provide a more detailed response after the hearing, especially when he didn’t know something offhand. “Offering to provide additional support offline shows that you are committed to seeing this through, and it’s not just going to be a one-off where you’re being cross-examined and then you’re going to disappear and go back to whatever you were doing,” Cohen said. “It shows you are committed to continue working on this.”