Much of [SEIU President] Stern's vision for labor is honed from his own experience battling employers. Consider the case of janitors. The union long had strongholds in major cities such as New York, where its 50,000 office-building janitors earn up to $18.57 an hour, plus benefits. But across the Hudson River in New Jersey, some 10,000 nonunion janitors make little more than the $5.15-an-hour minimum wage -- even though they're the same largely immigrant workers cleaning similar offices.

Four years ago, as part of a nationwide janitors' campaign, the SEIU set out to sign up the New Jersey workers. The union only had about 1,000 janitors in the Newark area and had done little to keep pace as corporate flight from Manhattan led to a boom of new offices in northern New Jersey. Stern knew he couldn't run a typical recruitment drive, one janitorial contracting company at a time: In this fragmented industry, any that agreed to higher pay would be quickly undercut by nonunion rivals.

So SEIU tackled whole markets at once. In 11 New Jersey counties, it told contractors that they wouldn't have to lift pay until the SEIU got 55% of those in their area to go along. The union then mounted strikes and rallies by would-be members and took other actions to try to force contractors to go along.

The first 55% trigger point was reached in 2001, and the union contracts took effect. By the end of this year, the SEIU will represent about 70% of northern New Jersey janitors, whose pay now ranges up to $11.75 an hour, plus benefits. While that's still far short of the Manhattan wage, the SEIU is realistic enough to know that lower-priced New Jersey can't support the same pay. Nonetheless, unionization "has been beneficial to the industry because we're not undercutting each other, turnover is down, and workers are more dedicated and loyal," says Mark Blackburn, marketing vice-president at CSI International Inc., a privately held custodial-services company based in Red Bank, N.J., that employs 2,000 janitors in a dozen states and is the SEIU's largest New Jersey contractor.

The janitor campaign is helping low-wage immigrants reach the mainstream. Rita Cortes, who came to the U.S. from Honduras 17 years ago, had been cleaning New Jersey offices for the minimum wage since 1988. When the SEIU contract kicked in three years ago, she jumped immediately from $5.15 an hour to $8, plus some benefits. Today, Cortes, 54, earns $9.75 as a nighttime office cleaner in Secaucus and will go to $10.75 in October. "Now my husband and I can eat better, and I get three weeks' vacation a year, which I never had before," says Cortes.