Jerry Slocum likes to cause trouble — with puzzles.

A celebrated collector, Mr. Slocum, 94, has so far amassed some 46,000 mechanical puzzles. He began collecting at age 8.

In one of numerous books that Mr. Slocum has written on the subject (often with co-authors), such puzzles are defined as “a self-contained object, composed of one or more parts, which involves a problem for one person to solve by manipulation using logic, reasoning, insight, luck and/or dexterity.”

Mr. Slocum’s favorite is the T puzzle. Also known as the Tormentor or the Teaser, it originated in the early 1900s as an advertising gimmick, and also just for fun.

A big capital T is cut into four pieces. The goal is reassembly.

“It looks pretty simple, but it’s not,” Mr. Slocum, a retired aerospace engineer, said on a Saturday morning last summer in downtown Houston.

He had just put a T puzzle on display at the latest International Puzzle Party. Mr. Slocum first threw this party on April Fools’ Day in 1978; just 10 people gathered in the living room of his Beverly Hills home, where he still lives. Now, more than 500 serious collectors are on the invitation list, and the event is organized by a rotating committee. The destination moves on a three-year cycle among the United States, Europe and Asia.

Last July, Mr. Slocum and about 100 puzzle zealots gathered in Houston at the Hilton Americas hotel, where they were trailed by a film crew. (A feature documentary, “Puzzle Party,” is in the works from director Logan Hall and producers Sarah Morgan Hall and Tim Warmanen of Put Together Pictures). This September, 167 puzzlers will meet in Japan. Details are kept confidential — there have been problems with party crashers and design pirates in years past, according to Nick Baxter of Hillsborough, Calif., a former software consultant and a central puzzle party organizer. Mr. Baxter first attended in 1993 at age 36 and has not missed a year since.

Stan Isaacs, a computer programmer who lives in Palo Alto, Calif., first attended in 1980, one of 19 puzzlers. Finding his tribe gave Mr. Isaacs permission to spend money on collecting. And it confirmed his life philosophy: “You can treat everything in life as a puzzle, especially computers,” he said. “I think that that’s a very pleasant way to be because it makes everything interesting.”

Two years later, the gathering grew to 30 people. In 1983, Kate Jones joined. “Jerry was an inspiration for everyone,” Mrs. Jones recalled. “He was very fierce.” Most collectors valued puzzles with a single solution, she added, but “I was at the other end of that.”

Mrs. Jones and her husband, Dick Jones, live in Pasadena, Md., and run a puzzle business called Kadon Enterprises. She designs many of their “gamepuzzles” (the company trademark) around shapes that can combine in seemingly infinite ways. “That is what I fell in love with,” she said. “You have the freedom to invent. You’re not in a totalitarian trap.”

A puzzling exchange

In 1986, when 55 people signed up, Mr. Slocum moved the party from his living room to a Los Angeles museum where his collection was on exhibit. The International Puzzle Party has since evolved into a weeklong extravaganza. The main attractions are the puzzle exchange on Saturday and the puzzle party proper on Sunday. The program also includes lectures, a design competition and local sightseeing.

For the puzzle exchange, everyone swaps with everyone. Collectors bring enough copies of a puzzle to match the number of participants, and one for display; it must be a new mechanical puzzle that is not commercially available. Many participants design and make their own.

“My grandson designed my puzzle,” Mr. Slocum said when a swapper approached that Saturday in Houston. “I think it’s quite ingenious. He’ll show you how it works.”

“We have a packing puzzle here,” said Matthew Slocum, 35, a computer scientist from Portland, Ore. The puzzle, Square Set, was based ion a geometry problem about the best-fit packing of unit squares in squares.

“Very neat,” said Steven Canfield, a urologist in Houston and co-host of the event. Dr. Canfield, who writes a blog called Boxes and Booze (“pairing craft cocktails with crafty puzzles”), reciprocated with a sequential discovery puzzle in the form of a cocktail shaker.

He commissioned the design and fabrication from Lee Krasnow, a puzzlemaker in Wayland, Mich. “We’ve got a lot going on in there,” Mr. Krasnow said. He describes his process as “puzzle-making tomfoolery,” but he considers the result more art than craft or toy. “I think good art is something that evokes emotion in somebody,” Mr. Krasnow said. “A lot of puzzle emotion is frustration, but then there’s the ‘Aha!’ Not many genres of art can provide you that ‘Aha!’”

‘Purposeful inefficiency’

In a sense, puzzles are about people giving one another grief — the joyful kind. “Play in general is the practice of seeking and causing mutually desirable sorts of trouble,” said Bret Rothstein, a historian of play at Indiana University Bloomington. Elaborating, he borrowed from a games philosopher, Bernard Suits, who praised the notion of purposeful inefficiency: inventing obstacles and difficulty so as to enable the pleasure of resolution (or even delightful nonresolution).

“We’re all gluttons for punishment as long as it’s punishment of the right kind: amicable, surprising, pleasing and, above all, open-ended,” Dr. Rothstein said in an email. “We puzzlers are just more overt about our appetites.”

Mr. Slocum’s puzzle appetite is “voracious,” Dr. Rothstein said. Yet he has taken a scholarly approach, researching his books and developing a puzzle classification system. In 2006, he donated the majority of his multitudes to the Lilly Library at Indiana University. Previously, the collection resided in a bespoke museum in his backyard. (His late wife, Margot, gladly gave up half her garden to get all those puzzles out of the house.)

Dr. Rothstein teaches two courses using the puzzle holdings. And in 2024, through the individualized major program, his student Matthew Hayden graduated with a degree in enigmatology, the study of puzzles. (In 1974, Will Shortz, the crossword editor of The New York Times, obtained the first such degree in enigmatology, a discipline he devised for his individualized major at the university.) “I owe a debt to Jerry Slocum,” Mr. Hayden said. “From my perspective, Jerry turned puzzling into a global subculture.”

The puzzles are available for interrogation in the reading room by appointment; the Slocum Room, with a hands-on puzzle cart and a rotating permanent exhibition, is open to the public daily. Every Friday afternoon, Andrew Rhoda, the puzzle curator, gives a tour. “Puzzles promote mathematical thinking and critical reasoning, and impart skills like patience and stick-to-it-iveness,” he said.

‘A lot of happy people’

On Sunday at the Houston event, the queue started early for the puzzle party, which is essentially an exclusive opportunity to buy limited edition puzzles. When doors opened at 9 a.m., puzzlers raced to the sales tables.

“I’m buying,” said Mr. Slocum, his wallet packed with $3,000 in mixed bills. He took his time. “I don’t buy a lot these days,” he said. “But sometimes I do, and send them to the Lilly Library.”

Many collectors rushed to the table of Perry McDaniel, an operations manager for a precision tools company as well as a puzzlemaker and member of the host team. In this setting, Mr. McDaniel, of Midlothian, Texas, goes by Puzzled Guy Bakery. He is known for his series of cake-themed creations (not edible) that are made to one-one-thousandth of an inch accuracy. The crowd snapped up his batch of 80 Red Velvet Cake puzzles in nine minutes, for $250 each. (One resold for $3,700 at a recent auction.) “It was a feeding frenzy,” he said. He saved a piece for Mr. Slocum. “Without Jerry, there is no me,” Mr. McDaniel said.

Mr. Slocum stopped to see Kagen Sound of Denver, Colo., and admire his Bookmark Box puzzle — part of his “operated box” series; there’s also Battery-Operated Box and Coin-Operated Box.

“Wonderful, I’ve got to have it,” Mr. Slocum said. He bought two. Total: $1,150.

For Mr. Slocum, the highlight of the 41st International Puzzle Party was the big picture: “I’m still alive, and the I.P.P. is still going,” he said. “There’s a lot of happy people.”

Happily troubled. One attendee was overheard asking another, “What state are you from?”

The answer: “Confusion.”