Ms. Sleeper said that agents from the inspector general had asked her whether Ms. Baumann had promised to promote her work in exchange for a discount. Ms. Sleeper said that the price was fair because the dress was relatively simple and not a traditional wedding gown, and that Ms. Baumann had not promised any favors.
The Smithsonian also took issue with the location of the ceremony at a property owned by a nonprofit — LongHouse Reserve in East Hampton, N.Y. — which has a long association with the Cooper Hewitt. Ms. Baumann was not charged a fee by LongHouse for the wedding, and she had allowed the nonprofit use of the Cooper Hewitt conference room, without charge, for board meetings.
The Smithsonian, which was created by Congress and is partly funded by the federal government, has a conflict of interest policy that says “employees must not engage in private or personal activities that might conflict, or appear to conflict, with Smithsonian interests, such as using Smithsonian employment for private gain” or “giving preferential treatment to any person or company for any reason.”
In her resignation letter, Ms. Zankel wrote that “to say the punishment does not fit the crime is an understatement.” She also asked whether there could be “a touch of misogyny here.”
“Can you imagine all this brouhaha about a dress and a wedding directed toward a man in the same position?” she wrote. “I think not.”
Along with Ms. Zankel, those who resigned from the board were Mr. Rockwell; Jon Kamen, the founding chairman and chief executive of RadicalMedia, a production company; Francine S. Kittredge, the founder of the Neuberger Berman Foundation, which helps at-risk youth; Avi N. Reichental, a pioneer in 3-D printing; and the author Kurt Andersen.
“I joined Cooper Hewitt because of Caroline’s inspiring, transformative, visionary and infectious leadership,” Mr. Reichental wrote in his resignation letter. “She is a kindred spirit that continues to remind me and rekindle in me the importance of design, creating and making in every part of our lives. “