Residents of Cambridge's model neighborhood last night took the first tentative steps toward creating the agency which will run the model cities program.

Some 150 residents of the model neighborhood--a 268-acre area near Central Square--attended a mass meeting to discuss plans for the election of representatives to the City Demonstration Agency--the board which will operate the program. Last spring, the City Council guaranteed residents of the model neighborhood a majority on the agency.

The City has scheduled a series of such meetings throughout the month, to be followed by a convention which will set up the plans for the elections. After a referendum on the convention's results, the City Council will pass the ordinance creating the model cities agency. Election of the neighborhood representatives on the agency will follow.

The meeting was sharply divided over a proposed voting age of 18 for the elections. After a heated exchange, one resident pleaded, "Let's keep out cool. We are all in this together--we are all citizens of Cambridge--let's stick together."

Throughout the evening, Justin M. Gray, assistant to the city manager for community development, tossed ideas back to the audience, telling them, "It's your decision."

Gray later commented that "this could have been done by City Hall, but this process, which looks tortuous, is what I believe in." He said he felt that Cambridge's plan for electing the majority of the governing agency will be superior to the appointment of Boston agency members. "The people have to know that they are running this program," Gray said.

To date, the Federal Government has given Cambridge only $91,000 of the $235,000 requested to plan the model cities program. Unless the City gets more money, Gray said, some of the programs suggested in the City's application to the program will have to be discarded. He is now negotiating with the government for at least $30,000 more and is also approaching foundations for more money. But, he admitted, "it's discouraging."

Cambridge will have one year from the day the Federal government returns its model cities contract to set up the agency and plan its program. Gray suggested last night that the elections be held within the next two and a half months to leave adequate time for planning.

After the plans for the program are completed, the residents of the model neighborhood will be able to veto them in a referendum. If the plans are approved, it wil take some eight to ten years to carry out the program.