Some reclamation efforts have shown success. Daryl Baldwin started working to revive the dormant language of the Miami Nation in the Midwest (part of the Algonquian language family), and taught his own children to speak it fluently. He now directs the Myaamia Project at Miami University in Ohio, a joint effort between academics and the Miami tribe.

Farther east is Stephanie Fielding, a member of the Connecticut Mohegans and an adviser on the Stony Brook project. She has devoted her life to bringing her tribe’s language back to life and is compiling a dictionary and grammar book. In her eyes language provides a mental telescope into the world of her ancestors. She notes, for example, that in an English conversation, a statement is typically built with the first person  “I”  coming first. In the same statement in Mohegan, however, “you” always comes first, even when the speaker is the subject.

Image “Conversion of the Indians,” an early depiction of some of the original inhabitants of Long Island. Its exact date is unknown. Credit... Long Island Collection, East Hampton Free Library

“This suggests a more communally minded culture,” she said.

Now in her 60s, Ms. Fielding knows firsthand just how tough it is to sustain a language effort over time, however. She said she was still not fluent.

“In order for a language to survive and resurrect,” she said, “it needs people talking it, and for people to talk it, there has to be a society that works on it.”

Chief Wallace of the Unkechaug in Long Island already has a willing student from a younger generation. Howard Treadwell, 24, graduated from Stony Brook in 2009 with a linguistics degree. He will participate in the Long Island effort while doing graduate work at the University of Arizona, where there is a specialized program researching American Indian languages.

Mr. Treadwell is one of 400 registered members of the tribe, which maintains a 52-acre reservation in Mastic, on the South Shore. The Shinnecocks have about 1,300 enrolled members and have a reservation adjacent to Southampton.