The American Association of Museums has told its members that courting megabucks donors is a necessary but risky venture that museums must navigate carefully.

The country's largest museum organization said Wednesday that museums should make their relationships with donors "open, available and understandable to the public."

This is not an easy time for American museums. Finances are unpredictable. Foundations and governments are not as generous as they were in the 1990s. But civic leaders and politicians still point to museums as an entertainment and economic draw.

The public is demanding more from museums -- blockbuster shows, educational programs and amenities such as cafes. Many museums are expanding, which often means recruiting more donors. In some cases, these are successful people who have not been patrons before.

Yet those relationships have often landed museums in hot water. Earlier this year, the Smithsonian was rocked by the withdrawal of a nearly $38 million pledge from Catherine B. Reynolds. The gift to the National Museum of American History had split the staff, a majority of whom questioned her idea for a hall on American achievement. When the two sides couldn't compromise on how much input curators and donors would have, Reynolds withdrew her donation.

Wednesday, acknowledging the predicament of many museums, the AAM strongly advised museums to develop a clear and uncompromising hands-off policy for their donors. In a directive called "Guidelines for Museums on Developing and Managing Individual Donor Support," the group advised its 3,000 members to avoid all conflicts of interest and to put their integrity above the much-needed dollars.

The AAM asked for transparency on both sides, with the museums spelling out what donors can expect for their support, including the murky area of naming.

Edward H. Able Jr., president of the Washington-based group, said the organization was trying to bring clarity to an issue that has cropped up with increasing regularity. In some cases, donors have wanted a more active role in the museums. Watchdogs, meanwhile, have raised questions about the independence and commercialism of institutions.

"We today have a new generation of donors, and they are not as knowledgeable about the appropriate relationships between the donor and the museum," Abel said. "And that has more to do with the more complex relationships and arrangements that are now a part of the donor relationship with the nonprofit community." A primary concern of the museums was maintaining what Able called "independence from outside interference in operation and content."

In the area of naming, the guidelines do not discourage recognition but say the acknowledgment has to be decided on a case-by-case basis.

However, the guidelines do emphasize that museums should question the use of anonymity. "A museum should avoid agreeing to requests for anonymity that conceal a conflict of interest, real or perceived, or raise other ethnical concerns."

Giving USA, a group that tracks and analyzes philanthropy, reported that Americans gave $212 billion in 2001, with individuals accounting for 75 percent of that total. Individuals gave $161 billion, slightly less than in recent years. Corporate giving fell 12 percent in 2001. Contributions to the arts from foundations, corporations and individuals was $12.14 billion, up slightly from the previous year.

"The entire nonprofit community has been put on notice that there is considerable risk in 'co-branding' your institution with another individual, be that an individual or corporation," Able said.

Virginia Clark, the newly appointed director of external affairs at the Smithsonian, said the AAM directives "touched on all the important issues." The question of donor relationships is under review at the Smithsonian, she acknowledged.