Jack Carlson, excecutive officer and chief economist of the National Association of Realtors, resigned yesterday after seven years as the top administrator of the NAR, which is the country's largest trade association.

Carlson, who directed the association through one of the real estate industry's worst recessions, had worked to bring the NAR into the political arena, mobilizing the association's roughly 700,000 members and immense political war chest in support of private property rights and tax advantages for the industry.

Clark E. Wallace, the new president of the association, said Carlson gave the NAR leadership a letter of resignation several weeks ago and that they decided to accept it earlier this week. Carlson and Wallace referred to the decision as "amicable" and the settlement terms as "fair."

"I came to the NAR for a challenge seven years ago, and I feel as though my contribution has finished," Carlson said. "I'm off looking for a new challenge."

William D. North, the association's general counsel, has been named interim acting CEO.

Neither Carlson nor Wallace would say what the settlement terms were or what Carlson had earned during his tenure with the NAR, but an industry source who worked with Carlson said he had earned more than $200,000 a year.

"The NAR is the biggest trade association in the country, and he was paid well," Wallace said. "He was hired to bring the NAR into the 1980s, and he did that, and now he is going on to find a new opportunity."

The NAR's lobbying effort has been criticized recently by some other members of the real estate industry as "too uncompromising" and too aggressive. One real estate lobbyist, who spoke on condition of anonymity, said that, under Carlson's direction, the NAR had been "difficult to form a coalition with, because they won't ever give on any of the issues."

Wallace said that, in replacing Carlson, the NAR would look for an administrator who would focus on consolidating the association's many different activities.

Donald H. Treadwell, the 1984 president of the NAR, said the association needs someone who can manage the NAR's business interests "as a business, rather than just as a trade association."

Industry sources said they were not surprised by Carlson's resignation, and many said they knew that a faction at the NAR had been pushing for new leadership for the past two years.

Wallace, however, said that there was "no bad blood" between Carlson and the NAR board and that the association does not anticipate any major shift in its work or operation. Wallace said a search committee already is looking for a new CEO and that the NAR expects to hire someone by early summer.