Experts described the little-noticed changes as marginal improvements, but important ones, and said they promised to aid the long-term jobless and help hold down the unemployment rate in future recessions. “We’ve had the same unemployment insurance system since the 1930s, and it really was designed for a different time,” Alan B. Krueger, the chairman of the White House Council of Economic Advisers, said in an interview. “Most people on unemployment insurance back then had been temporarily laid off from manufacturing jobs. Obviously, that’s not true now — these are people who are often moving into a whole new industry.” The bill, which passed Congress on Friday and President Obama has said he will sign, allows states to use unemployment insurance money for programs that help move the jobless back into the work force. Such programs, like Georgia Works, often offer employers wage subsidies for taking on and retraining jobless workers. The bill also requires states to reassess the eligibility of workers for their unemployment insurance — confirming, for instance, that a person receiving long-term benefits is actively searching for a job. That reassessment provides an opportunity to tailor career counseling and other re-employment services to the long-term jobless. The bill additionally expands “work sharing” programs that can help reduce layoffs at big businesses. In effect, businesses would have the option of cutting the hours of five workers by 20 percent each, say, rather than laying off one worker. The business could then use unemployment insurance money to help supplement the workers’ wages to make up for the lost hours. The changes were a product of intense partisan wrangling, but have won bipartisan support since the bill’s passage. Representative Dave Camp, Republican of Michigan and one of the bill’s primary negotiators, described the reforms as “historic” in a statement, saying that the changes would “help the unemployed get the training and resources they need to move from an unemployment check to a paycheck.” Many conservative economists and research groups have applauded modernizing the unemployment insurance system and reorienting it toward helping jobless workers find new employment through the kinds of provisions included in the bill. President Obama, who has repeatedly called for turning the unemployment insurance system into a “re-employment insurance” system, also described the “important reforms” as a victory on Tuesday. Experts doubt that the changes will do much to wrench down the current unemployment rate or solve the long-term unemployment crisis. Only strong economic and jobs growth will do that, they said. But they said that the new provisions could help encourage employers to hire some of the 43 percent of unemployed workers who have been out of a job for more than six months. Moreover, the changes could help to reduce layoffs down the road. Work force experts say the current unemployment insurance system does little to help workers search for jobs, or to consider new industries or acquire new skills, if need be. “Today, our re-employment services mostly happen online or on the phone, and in groups,” said George Wentworth, a senior staff attorney with the National Employment Law Project. “Twenty-five years ago, you actually had hands-on assistance,” he added. Mr. Wentworth said the new provisions to assess the needs of long-term unemployed workers might help some of them expand their job searches. “If they’re someone who’s holding out for a specific industry or occupation, there will be someone to point out that the demand is not there, and to help them broaden their expectations.” Economists also applauded the work-sharing provisions, which have found success in states including Connecticut and Rhode Island as well as in countries like Germany. “Work sharing is an incredibly smart thing to do,” said Heidi Shierholz of the Economic Policy Institute, a research institution in Washington. “But it’s a tragedy that we didn’t do that on a large scale over the past four years.” The provision may help reduce layoffs in the coming years, Ms. Shierholz said, supporting the recovery. She also said that being laid off tended to hurt a worker’s earnings and career prospects down the road. Work-sharing helps to minimize economic pain and keep families afloat, she said. The bill maintains a two-percentage-point payroll tax cut for 160 million wage-earners through the end of 2012. It also keeps additional weeks of unemployment insurance for the long-term jobless, though it starts to taper the maximum weeks of benefits to 73 from 99. Additionally, it prevents a sharp drop in reimbursement rates for doctors who accept Medicare. The bill contains other changes to the unemployment insurance system, as well. It allows states to screen and test unemployment insurance recipients for drug abuse, in certain cases. But it does not require people receiving unemployment insurance to enroll in a high school equivalency program, as some politicians had suggested. The White House has previously called for a much broader range of policies to aid the long-term unemployed and help American workers upgrade their skills, including the American Jobs Act released in the fall. “My message to Congress is: Don’t stop here, keep going,” Mr. Obama said Tuesday, calling on Congress to keep passing provisions to aid workers.