For thousands of undocumented immigrants who rushed to apply for new protections from deportation, Wednesday was the life-changing day many had dreamed of for years.

But for most, it was just Wednesday.

“I will be working today, that’s all, if I can get work,” said Ricardo Cruz, 22, a Salvadoran day laborer gathered with other job seekers in a parking lot on New Hampshire Avenue in Langley Park. “I have heard of this program, but they said it was not for me.”

Advocates hailed President Obama’s offer of temporary residency and work status to some young immigrants as the most significant reform in a generation. But, as some have learned as the details became clear, it is a narrowly tailored one.

Fewer than 2 million of the estimated 11 million undocumented immigrants in the country are eligible for the program, known as deferred action, which began accepting applications Wednesday.

That leaves life in the shadows to continue unchanged for the rest. For many who have been waiting to learn the final details of the program, its launch brought crushing disappointment.

“It was devastating to hear I didn’t qualify,” said a sobbing Elsi Hernandez after her visit to Carecen of Columbia Heights. Hernandez, 25, came to the United States when she was 17 and graduated from high school in 2008. She only learned while gathering documents to apply that she was too old when she arrived from El Salvador to be eligible. “I just want to study and be a good example to my daughters.”

The program, hewing closely to the goals of the long-debated Dream Act, targets those who were brought here as children. It is open to immigrants ages 15 to 31 who arrived before they were 16 and have lived here continuously for the past five years or more. Among other restrictions, they must be free of serious criminal convictions and be in school or have a high school diploma or equivalent.

That amounts to about 1.7 million immigrants, about 15 percent of the illegal immigrant population, although no one knows how many of those will actually apply.

“It’s a lot of people, but it does leave the vast majority of the undocumented population still undocumented,” said Jeffrey Passel, senior demographer of the Pew Hispanic Center. “Most of the undocumented immigrants in the country now are people who came here as adults on their own.”

At legal clinics and workshops around the region Wednesday, families and young adults came by the hundreds to learn if they would qualify for the program. The biggest group who won’t are those who are too old: An estimated 6.8 million undocumented immigrants are 31 or older.

But many of those have children and showed up eager to find out how to sign them up. Even as advocates explained that many of the youngsters were eligible, they were counseling families to mix their joy with practical thinking.

“This is an extension of the split families we’ve had under our immigration system for a long time, where you have children who are citizens and parents who are not,” said Jeanne Atkinson, head of immigration services at Catholic Charities D.C. More than 50 people showed up at the group’s Mount Pleasant office Wednesday to talk to volunteer attorneys about the program. “You have to have a plan. What are you going to do if you are deported? Who is going to be the guardian of your children?”

Antonio Aleman, 43, of Suitland, planned to apply immediately for his children, Beatriz, 21, and Erick, 15. The former police officer from Chalatenango, El Salvador, brought a neat stack of documents to a workshop Wednesday evening at CASA of Maryland in Langley Park. But his excitement was tempered by the realization the system would now treat him and his wife differently than their two children.

“I am happy because our children may be eligible to get a work permit and be here legally,” he said. “But it would be devastating to us to be away from our children.”

Many immigrants learned that they were in the right age bracket but fell short on educational requirements. An estimated 320,000 of them would qualify for the program if they could get their diploma through GED courses, according to Pew statistics. Some were scrambling to find documents proving they hadn’t left the country for any significant periods in the past five years.

“Controlled elation,” is how Thai Nguyen described the first day of application counseling at the USA Immigration Services Group office in Falls Church.

Back in Maryland, at the parking lot on New Hampshire Avenue, none of the 14 men gathered in hopes of picking up work had plans to apply for the program. Most said they were older than 15 when they crossed the border, and some had traveled back and forth several times with the ebbs and flows of the economy. None seemed to have any sense that immigration reform, no matter how limited, had anything to do with them.

“I’m happy if they can stay with their family,” Cruz, the Salvadoran day laborer, said of those eligible for the new program. He came here with his brother five years ago and hopes to return soon. “That’s where we all want to be.”