"Copreneurs": they're those dynamic husband-and-wife teams who run businesses together. There are at least a quarter million of them in the United States, and they're supposed to be pioneering a new model of marital and business equality.

Hogwash, says Kathy Marshack, a Vancouver, Wash., psychologist who counsels owners of family businesses. "It's a bunch of hype." In an academic study of 30 couples, she found that copreneur relationships are significantly less egalitarian than dual-career marriages. Copreneurs actually bear a closer resemblance to Ward and June Cleaver, with Mom washing the dishes and balancing the books while Dad fights the competitive wars.

For instance, 83% of the copreneurial wives surveyed were solely responsible for general housework, compared with 49% of wives with their own separate careers. When it came to handling all the household shopping, that disparity was 64% for the copreneur wives, versus 36% for the other working wives. And at work, copreneurial women typically performed the chorelike tasks, like payroll and billing. "One copreneur wife told me her mission was to showcase her husband's talent," says Marshack. "That's pretty typical. Anybody who's been out there working with these couples knows they're not egalitarian at all."

The gender attitudes of copreneurs were very traditional, Marshack found, while those of their dual-career counterparts were more flexible, with each spouse displaying qualities more typically associated with the opposite sex. The explanation? Marshack theorizes that it has to do with people's need to set boundaries between love and work. Dual-career couples, she explains, cross a well-defined boundary every day when they leave home for the office. In the absence of such a physical boundary, "copreneurs instead rely on a conceptual boundary based on gender differences."

Most of the popular writing about husband-and-wife partnerships, she complains, takes select interviews with exceptionally egalitarian couples and from them, makes incorrect generalizations about all spousal ventures. "A few couples I talked to did succeed in dividing responsibilities evenly, but those are the exceptions," says Marshack.

The more sobering reality, she says, is that copreneurial ventures usually work most smoothly if the wife wants to be "the behind-the-scenes woman who is happy to let her husband run the show." Bringing a stronger, career-woman sensibility to the partnership--and dividing tasks according to ability, not stereotypes--is, according to Marshack, incredibly difficult. "You can try to do it, but you'll probably fight a lot more."