The use of full-time seasonal workers is expanding as companies seek to keep wage and benefit costs low, meet their peak demand cycles and avoid some pitfalls of temporary workers.

Seasonal workers already are a staple of the retail, hospitality and tourism sectors, as well as weather-related industries such as construction and agriculture. Now manufacturers increasingly are turning to such workers -- from concern about a shortage of skilled workers and a need to sustain productivity gains.

Even with the economy growing, companies remain cautious about hiring, particularly in the highly competitive goods-producing sector. In some cases, workers who want full-time work year-round can only find seasonal or temporary opportunities.

Indeed, from an employer's perspective, using seasonal full-time workers lessens overall labor costs from having workers employed year round. It also cuts the expense of recruiting and training new batches of temporary workers and helps employers hold onto more experienced, skilled workers who are retired or want to work only part of the year.

There are no firm numbers showing how many companies use seasonal full-time workers. The Labor Department lumps them together with year-round full-time workers. The number of temporary employees, which doesn't include seasonal workers hired directly by companies, also continues to grow, as it has for two years.

And anecdotally, employers and analysts say the use of seasonal full-time workers appears to be gaining speed. "It's become much more acceptable to have short-term working relationships," says Arne L. Kalleberg, a professor of sociology at the University of North Carolina-Chapel Hill.

Daniel Meckstroth, chief economist with Manufacturers Alliance/MAPI, a public-policy group in Arlington, Va., says there is a labor-market niche for workers who don't want to work year-round but need income. "The question is, 'Can you make that arrangement attractive enough?' " he says.

Sony Electronics Inc., a unit of Tokyo-based Sony Corp., plans to hire 500 full-time seasonal workers at its plant near Pittsburgh during its peak season of August to January. Workers will be offered $8.25 an hour, health-care benefits, paid vacation and the company's 401(k) retirement plan. In the off-season, workers can extend health-care benefits through Cobra, the program that provides continued health coverage at group rates to former workers.

"The seasonals is a group that we hope will come back year after year, and it's also the group from which we'll be picking full-time staff," says Michael Koff, spokesman at Sony Technology Center.

Doing so will help Sony to meet increased demand for its rear-projection television sets, while reducing the cost of temporary workers, the company said. Last year, it hired about 1,900 temporary workers during its peak season and had to bus in workers from Baltimore and Cleveland, paying their transportation and lodging costs, on top of staffing-agency commissions.

Smaller companies, too, count on full-time seasonal workers to help them through transition periods. For example, Lake Champlain Chocolates in Burlington, Vt., plans to add a second shift but now only needs that shift during the peak candy-buying season that runs roughly from Halloween through Easter. Rather than hire full-time workers to whom it must pay wages and benefits during slow months, the 100-employee company adds 20 full-time seasonal production employees to work between August and March.

"We've been lucky there are people that are looking for a seasonal job," says John Weishaar, production manager.

Even businesses that don't have much variation in production schedules want full-time seasonal workers, because they can be more reliable than temps. John Evans' Sons Inc., an industrial-spring maker in Lansdale, Pa., is hiring seasonal full-time workers to replace local students used in the past.

Students "are either at the shore" or seeking out internships, says Allan Davey, president of the company. Full-time seasonal workers will be used to produce parts for windows, trucks and elevators when year-round workers take vacations. The company doesn't offer them benefits, but pays them 10% more than starting full-time workers.