For decades America has been steadily approaching a major social development — a time when the number of women in the work force would surpass the number of men. That moment has now arrived, brought on by, of all things, a recession.

Three-fourths of all the jobs lost in the recession were held by men as male-dominated industries such as construction, manufacturing and banking took a beating. Scores of women had to enter the work force, or postpone leaving it, to make up for lost household income. Many even entered the work force as an insurance policy against the threat of their husbands being laid off.

Now, women are half of all U.S. workers, and mothers are either primary breadwinners or co-breadwinners in two-thirds of American families. At the same time, more dads are stepping out of the traditional mold and taking more active roles in their children’s lives. Couple those changes with the realities of the so-called sandwich generation, wherein adults are caring for their children and elderly parents, and it’s little wonder some observers say we’re on the cusp of a social change on par with the industrial revolution, the civil rights movement and the emergence of the Internet.

Against this backdrop, the dynamics of how a business operates and how families function are facing a tidal shift, yet the changes are occurring within a societal model that was built in the 1950s. Most schools still send children home around 3 p.m., close for two weeks at Christmas and shut for three months in summer. Few doctors’ offices are open past 5 p.m. That was all manageable when one parent stayed home, or when the expectation was that mothers would take time off for such family matters. Now, however, the modern workplace is occupied by women and men trying to balance work with checkups, ballet practice and soccer games. That leaves employers with the tricky task of adapting to a new reality, or rigidly holding on to the status quo, perhaps at their peril.

Simply put, an organization cannot expect to keep good and happy workers if it’s ignoring the needs of its employees to meet family obligations.

“The majority of today’s employers still need to accept that there is more than one way or one place that work can get done,” says Karen Skelton, executive producer of “The Shriver Report: A Woman’s Nation Changes Everything” and a managing partner with Dewey Square Group. “The good news is it’s no longer heretical to talk about flex schedules or family leave, but the U.S. is still far behind other countries on this subject, and we’ve become less competitive for it.”

Recently, a poll by Time and the Rockefeller Foundation found that regardless of gender, employment status or political affiliation, employees desire more flexibility in work schedules, paid family leave, and increased child care support. That result isn’t a surprise, and polls rarely have a major effect on how businesses operate. Politicians, however, are another matter.

Responding to the changes in American families, President Obama has charged the Office of Personnel Management with exploring the issue; there’s potential for new federal policies on the eight-hour workday to family-friendly employee benefits. Few employers are likely to welcome that kind of government boot on their thresholds.

“Businesses shouldn’t have a fear about government coming in and mandating something,” Skelton says. “If they don’t adapt on their own, they’re going to lose good workers. That’s just a fact.”

In contrast, companies that make it possible to balance work and family have found it’s a philosophy employees find very attractive. Reznick Group PC, a national accounting firm that prides itself on having a higher percentage of female partners than other accounting firms in the U.S., took a fairly progressive approach to helping employees balance work and family needs in the early 2000s. It was a decision Beth Mullen, a managing principal in the company’s Sacramento office, says the company had to make to retain its best talent.

“It was a time when competition for top talent was especially fierce, and we couldn’t afford to lose employees,” Mullen says. “We created a variety of flexible arrangements and employed technologies that relied less on paper and enabled employees to work from home.”

Equally important is that employee retention, by definition, helps employers avoid the cost of turnover, including fading customer confidence, lost productivity and the financial investment required to hire and train a new employee.

Beyond retention, however, experience suggests companies that accommodate family demands have more loyal employees.

“A couple hours off for an employee to go to a recital means little to the organization, but it’s huge for that family,” says Gene Marcucci Bell, a senior vice president and regional manager with California Bank and Trust. “If I can give that to them, they’re willing to give back to the company, but if I’m rigid about it, I can expect them to be equally rigid in their behavior toward the organization.”

Companies wanting to create a family-friendly environment may not need formal policies, although having them can certainly help one organization stand out over another. The key word seems to be autonomy, with employees measured by their ability to manage time and produce results, rather than log hours in the office.

Even in professional services firms, where time is the product, some signs of change are appearing.

“As a company we try to be as supportive as possible,” says Jennifer Duggan, a mother of two and partner with Porter Scott. “Associates and staff can use paid time off however they like, and we try to work as a team so even if things are slammed in the workplace, we can schedule around that.”

According to the Shriver report, most workers under 40 have never known a workplace without female bosses and colleagues. The Rockefeller/Time poll found that both men and women agree that more women entering the work force is good for the country.

“The battle of the sexes is over, and it came out a draw,” Skelton says. “What we have now is more negotiation between the sexes about work, family, household responsibilities, child care and elder care.”

What some might call negotiation, others would simply call planning and management.

“The battle of the sexes may have ended in a draw, but it’s one that’s more satisfying for everyone,” Bell says. “Men get the best of having the kind of family life that wasn’t socially encouraged in the past, and women get the rewards of being challenged with work. Balancing work and family, together, leads to a much richer and fuller life.”

That’s certainly true for Kathy McKim, vice president of external affairs with AT&T, which was recently named one of the “Top 50 Companies for Executive Women” by the National Association for Female Executives. Three years ago, the company transferred her to Sacramento from San Antonio, and she and her husband agreed that she would be the sole breadwinner and her husband would be a stay-at-home dad. Most importantly, she says, it’s been wonderful for their family.

“When we were both working, my husband barely saw our daughter,” McKim says. “Staying at home has given them the chance to really reconnect with each other.”

One finding in the Shriver report highlights an area where there is a difference of opinion between men and women. Specifically, while men are doing more to help at home, they seem to think they’re helping out much more than they really are — at least according to women.

Despite all the change, women still bear the primary responsibility for managing the household. That, coupled with the increased responsibilities of work, is triggering concerns for women’s health in general.

“As women take on more in the workplace, while caretaking at home, caring for elders, they’re constantly ‘on’ and facing more stress,” Skelton says. “That’s one of the bigger reasons why women are suffering so much more from anxiety and depression.”

Although the rise of women in the workplace is almost unanimously praised by both sexes, the Shriver report found that three-quarters of Americans — men and women of every political stripe — say the decline in the percentage of children growing up with a parent at home is negative for society. To some degree this is balanced by more involved fathers, but the prospect of a new generation of latchkey kids is met with concern.

The concern underscores the need for employees to have the support of their workplaces now and for the foreseeable future. According to Skelton and other observers, the tidal shift the nation is experiencing now will be permanent and all of our most fundamental institutions —business, government, education, health care, the media and faith institutions — simply must respond and adapt to it.