What Is Improv? A Complete Guide
Improv is unscripted theater made up on the spot. Here's what it actually is, how it started, the main forms, and how to try it yourself.
Improv is theater made up on the spot. Nobody has a script. The actors walk on stage, get a suggestion from the audience, and build scenes in real time.
That’s the whole thing. Everything else is detail.
A fast definition
Improvisation — improv, for short — is performance that is created in the moment of performance. The performers don’t know what they’re going to say before they say it. Sometimes they don’t even know what the scene is until they’re in it.
In theater terms, it’s the opposite of a play. A play is planned. An improv scene isn’t.
In life terms, improv is what you’re already doing most of the time. You didn’t know yesterday what you were going to say at lunch today. You opened your mouth and stuff came out. That’s it. That’s improvisation. Stage improv is just the same thing, trained.
Where it came from
The modern form of improv as we know it started in Chicago in the 1950s.
Viola Spolin was a theater teacher and activist who developed a series of games to help actors be more present, more reactive, more alive on stage. She wasn’t trying to invent comedy. She was trying to fix what she saw as the deadness in theater training. Her book Improvisation for the Theater (1963) is still in every improv teacher’s bag.
Her son Paul Sills took her games and helped start The Compass Players in 1955 in Chicago — the first professional improv troupe. When Compass fell apart in 1959, Sills co-founded The Second City in 1959 with Bernard Sahlins and Howard Alk. That’s the one that became a comedy institution. Belushi. Aykroyd. Murray. Radner. Every SNL you’ve ever laughed at traces back to that basement theater.
Meanwhile in the 1960s, a director named Del Close started pushing improv into something longer and more ambitious. He wanted to build full pieces out of improvised scenes that connected thematically — not just five-minute party games. He invented the Harold, a 30-minute long-form structure, and eventually co-founded iO with Charna Halpern in 1981. He taught Tina Fey. He taught Amy Poehler. He taught Stephen Colbert. He taught the founders of the Upright Citizens Brigade.
On the west coast, Gary Austin started The Groundlings in Los Angeles in 1974. That one produced Will Ferrell, Kristen Wiig, Maya Rudolph, Phil Hartman, Pee-wee Herman.
Across the Pacific, a British-Canadian director named Keith Johnstone built a completely different school of improv in Calgary. His version was more competitive, more theatrical, less comedy-centric. He invented Theatresports in 1977 — a format where two teams improvise scenes against each other, judged by the audience. Theatresports is now played in dozens of countries.
Those are the four roots: Chicago’s Second City, Chicago’s iO, LA’s Groundlings, Calgary’s Loose Moose. Everything else is downstream.
The two main kinds: short-form and long-form
Most improv falls into one of two buckets.
Short-form is what you’ve probably seen on Whose Line Is It Anyway?. Individual games, each about 2 to 5 minutes long, each built around a single rule. “Scenes from a Hat.” “Questions Only.” “Party Quirks.” The host pulls a game, the performers play it, everybody laughs, next game.
Short-form is fast. It’s forgiving. It’s the easiest entry point for new improvisers because the game tells you what to do. If you’re stuck in a scene, the rule is always right there: only speak in questions. Every line rhymes. One of you can only say three words at a time. The constraint does some of the work.
Long-form is bigger. A long-form show is typically 25 to 60 minutes of connected improvised material. No games. No rules announced to the audience. Just scenes that build on each other, themes that emerge, characters that come back. The Harold is long-form. So is the Armando, La Ronde, the Monoscene, and dozens of others.
Long-form is harder and more rewarding. You can’t hide behind the game. The ensemble has to listen, commit, and build. When it works, it feels like a play that’s being written in front of you. When it doesn’t, it’s a bunch of people flailing for twenty minutes.
Most serious improvisers train in both.
The core principles
Every improv school teaches the same handful of fundamentals. The language varies. The emphasis varies. The core is pretty consistent.
Yes, And. Accept what your partner gives you and add to it. If they say “I can’t believe you got us lost in the woods,” don’t say “I’m not lost” — that’s a denial, and now you’re fighting instead of improvising. Say “I told you the map was upside down.” Now you’ve accepted the woods, accepted being lost, and added a detail that makes it interesting.
Listen. You can’t Yes-And what you didn’t hear. Most bad improv is a listening failure. You were thinking about your next funny line and missed what your partner actually said.
Commit. Half-committed improv is painful to watch. Whatever you’re doing, do it fully. If you’re playing a priest, be the priest. Don’t wink at the audience.
Be specific. “I had a bad day” is nothing. “I saw my ex at the grocery store, and he was buying the same cereal he used to make me stop buying” is everything.
Make your partner look good. You’re not competing with them. You’re building with them. Their success is your success. The audience can tell within ten seconds of a scene whether the two of you are actually a team.
Follow the fear. Del Close’s line. The scene you’re most scared to do is probably the scene you should do. The safe choice is usually the boring one.
These aren’t rules. They’re training wheels. You learn them, you practice them, and then you learn when to break them.
The different schools of thought
If you take improv seriously long enough, you’ll notice that different theaters teach different versions of it.
- The Chicago school (Del Close, iO, Second City): Long-form, ensemble-heavy, “treat your partner as a genius,” finding the game of the scene, heightening.
- The UCB school (downstream of Chicago but codified): Base reality, the unusual thing, framing devices, pattern recognition. More game-theory-forward than iO.
- The Groundlings / west coast school: Character-first, sketch-crossover, big choices, TV-ready.
- The Johnstone school: Status, offers, theatresports, status transactions, narrative arcs.
- The Annoyance school (Mick Napier’s anti-rules position): Don’t bring premises, take care of yourself, react honestly, screw the rules.
None of these are wrong. They emphasize different things. A lot of long-career improvisers train across multiple.
Where you learn improv
If you live in a major city, there’s almost certainly an improv theater with classes. Check our schools directory to see if there’s one near you. Big ones in the US include Second City (Chicago, Toronto, Hollywood), The Groundlings (LA), UCB (LA), iO (Chicago), The Annoyance (Chicago), Magnet Theater (NYC), The PIT (NYC).
Outside the US, there’s Loose Moose (Calgary), Boom Chicago (Amsterdam), The Free Association (London), Hoopla (London), Impro Melbourne (Australia), and dozens more.
If you don’t live near a theater, you can still practice. Books help. Truth in Comedy by Close, Halpern, and Johnson is the long-form bible. Impro by Keith Johnstone is essential. The UCB Manual is excellent if you want the game-theory approach.
And you can practice solo. That’s why we built Improv Chat — to give you reps when you can’t get to a class. Ten mini-games that drill the fundamentals. You speak. The game listens. It scores you on the things real coaches score you on.
What it’s actually good for
Improv makes you a better listener. It makes you quicker on your feet. It makes you more comfortable with uncertainty, which is most of life. It’s good for anxiety. It’s good for public speaking. It’s good for leadership. It’s good for being a more fun person at dinner.
But really, the reason most people stick with it is simpler than any of that.
Improv is the fastest way to turn strangers into friends. You put six people in a room for three hours, make them play together, and by the end they have inside jokes with each other. That doesn’t happen in a yoga class. It doesn’t happen in a book club. It happens in improv.
That’s the thing. That’s why it spreads. That’s why people who did one workshop a decade ago are still telling you about it.
Try it
The simplest move: find a theater near you and sign up for a Level 1 class. Most places run them constantly. No experience needed.
If you want to get a feel for it without leaving your couch, play a game in your browser. Ten minutes. See what it feels like. The stage is wherever you are.