If long-term unemployment is cyclical, or tied to economic trends, stronger growth should help. But the European economy is not recovering quickly enough to pull large numbers of people back into the work force. When people do find work, it is often through temporary, low-paid contracts, which have sharply increased as employers have looked to cut costs.

“It’s worrisome because we’re talking about many people who have been out of work for a very long time,” said Stefano Scarpetta, the director of employment, labor and social affairs at the Organization for Economic Cooperation and Development. “Their skills can become obsolete. They get stigmatized. They risk being disconnected from the workplace and society, with negative implications for them, their families and the economy.”

Sales, Strikes, Bankruptcies

About 20 people bustled around the spacious offices of Animal Kingdom in a gritty suburb north of Paris. A photo of an angelic kitten was taped to a wall. Printouts of Labrador puppies and yellow pythons adorned another. A poster announced a “Miss Chicken” beauty contest.

Muriel Banuelos, an energetic instructor, decided a few years ago to turn the training center into a virtual pet boutique. As new trainees arrived, so did new ideas. The company’s faux catalog expanded from cats and dogs to include pythons and frogs. The team added services it saw while studying France’s 3.5 billion euro, or $3.8 billion, luxury pet services market: high-priced weddings, baptisms and birthday parties for dogs, as well as beauty treatments like mud baths and manicures.

“Pythons are our new best seller,” Mrs. Banuelos announced, as she convened seven employees around an oval table to scrutinize sales. “It’s becoming very à la mode to have a reptile in the house.”

She looked at a stack of invoices, including some orders from virtual companies that had not been paid. “If this keeps up we’ll go out of business,” Mrs. Banuelos said, handing the papers to two women with instructions to follow up. “What’s our strategy to improve profitability?” she asked the group.

The concept of virtual companies, also known as practice firms, traces its roots to Germany after World War II, when large numbers of people needed to reorient their skills. Intended to supplement vocational training, the centers emerged in earnest across Europe in the 1950s and spread rapidly in the last two decades. Today about 5,000 practice firms operate on the Continent, supported by government funds, with at least 2,500 elsewhere in the world, including the United States.