The way the monetarists describe it, the only thing that blocks the Federal Reserve Board from gaining control of the money supply, and thus inflation, is its staff and the man the critics regard as its eminence grise, Stephen Axilrod.

Because the board says it wants to control inflation, the monetarists argue that it must be the board's staff, with Axilrod as chief, that undermines its work.

But Axilrod, staff director for monetary and financial policy for the board, as well as for the Fed's policy-making group, the Federal Open Market Committee (FOMC), laughingly shrugs off conspiracy theories about why the Fed's decisions haven't always produced the desired results.

The reality, he said, is far more mundane: controlling the growth of money is an uncertain, complex task full of surprises from a real world that often doesn't behave as monetarist theory predicts it should.

Throw in the rapid deregulation of the terms financial institutions can offer on deposits, such as the new money market deposit and super NOW accounts, and money becomes even harder than usual to measure in a meaningful way, much less to keep it growing precisely as policy intends.

Axilrod, a trim, self-contained man of unfailing good humor, is keenly aware that he advises policy makers and has a prominent hand in carrying out policy. But he insists that he does not set policy.

"I feel very modest about whatever impact on policy I have ever had," Axilrod said. "Policy is made by the seven-member board or by the FOMC." In addition to the seven members of the Fed's board of governors, the open market committee includes the presidents of the 12 Federal Reserve district banks, five of whom have voting rights at any one time.

Axilrod's title is somewhat misleading because his staff only has about 10 members, including his secretary. But it is not misleading in terms of his powerful position at the Fed. Before each of the eight meetings of the FOMC each year, Axilrod, 56, who is an economist, prepares the so-called Blue Book, which contains an analysis and three recommendations for monetary policy for the period until the next meeting.

"I think I have managed to figure out how to present material to the FOMC so that they feel nothing is being left out and so that they do not feel trapped" into following a particular course, he said.

Axilrod has been providing these alternatives for about 15 years and under four Federal Reserve chairmen. At the start, in a more junior position, he wrote only first drafts, and gradually was given more authority. For the past five years or so he has been in charge.

"I think I do it right and well. That probably accounts for my survivability," he said.

About two weeks before each meeting, he begins putting together the Blue Book with the help of other staff members, including some who are not directly under his control. In fact, whenever Axilrod needs assistance, he can and does "borrow" just about anyone he needs.

The recommendations are based on the Fed's longer-term goals for money growth and the economy and on the short-term targets set at the previous FOMC meeting. "The meetings are a continuum," the staff director said, "and it would be rare if there weren't an alternative to encompass everyone's view."

In the give-and-take of the committee discussion, reaching a consensus often means finding intermediate, compromise figures for money growth, interest rate ranges and the other parts of the policy directive that the FOMC sends to officials at the Federal Reserve System's open market desk in New York.

The open market desk does the actual buying and selling of Treasury securities that changes the level of reserves available to the nation's banking system. It is through the control of bank reserves that the Fed tries to control growth of the money supply. Each day the financial markets are open selected staff members gather in Axilrod's office here for a telephone conference call with the open market desk officials and a designated Federal Reserve district bank president who is on the FOMC. During the call market conditions are discussed and those on the line decide what the desk should do that day to meet the Fed's short-term money growth targets.

For relaxation, Axilrod plays tennis and the flute and reads avidly. His tennis game, polished in years past when the Fed had a court it called its own just across the street, has been limited in recent years by problems with a bad disc in his back.

He and his wife, Kathy, a professional artist, live in Bethesda. They have a daughter and two sons, one of whom is an economist with the House Banking, Finance and Urban Affairs Committee.

Last year Axilrod was paid just over $59,000 a year, only slightly less than the governors' $59,500 and Chairman Paul A. Volcker's $60,663. Axilrod considers his job "challenging" and obviously enjoys it immensely. "I've been lucky here. I've had interesting jobs and they have been in a key area."

But he has been doing them for a long time, and some friends wonder if he might not be looking for new challenges somewhere else. After all, Axilrod has been at the Fed since 1952, after completing all the course work (but not a dissertation) for a Ph.D in economics from the University of Chicago, a bastion of monetarist thought. He could retire with a full pension at any time. But he said, "I'm quite content in my job. I have no reason to leave and no reason not to leave. But I am a difficult person to place . . . . After being a key person in a large, ongoing operation, I don't want to sit on the sidelines."