What has been less apparent, though, is how harassment and the gender gap are inextricably linked. In fact, management experts and executives say, harassment can be a direct side effect of a workplace that slights women on everything from pay to promotions, especially when the perception is that men run the show and women can’t speak up.

Putting more women into executive ranks where they can have a greater collective voice goes hand-in-hand with making workplaces feel safer and more inclusive, says Kat Cole, chief operating officer and president of North America for Focus Brands Inc., whose chains include Cinnabon, Jamba Juice and Auntie Anne’s.

“You can’t separate them,” she says. “When women see other women in a position of leadership, it reframes what they think is possible to them.”

The fourth annual Women in the Workplace survey from LeanIn.Org and McKinsey & Co. offers a comprehensive look at both the prevalence of harassment and the persistence of workplace inequality. More than a third of women surveyed say they have been harassed at some point in their careers, and in male-dominated jobs those numbers are even higher. Among women in technical roles, 45% reported experiencing harassment, while 55% of women in senior positions did.

“This is about power,” says Rachel Thomas, president of LeanIn.Org, the nonprofit founded by

Facebook
Inc.’s

Sheryl Sandberg to support women in their career ambitions. “And there is still a dramatic power imbalance in the workplace.”

While women and men enter the workforce in roughly equal numbers, women fall behind in promotions from the very first step onto the management ladder, the Lean In and McKinsey data show. By the senior-manager level, men outnumber women two to one, and in the C-suite, just 22% are women.

The drop-off is even more precipitous for women of color, who get just 4% of the highest-level jobs. Even in industries where women significantly outnumber men, such as health care and retail, men still prevail at the top.

One in five women say they are often the only, or one of the only, women in the room or a meeting—and women commonly in those situations are at greater risk of harassment and more subtle forms of discrimination, the data show. That solitary experience is even more common for those who are senior executives. About 40% say they are often the only woman in the room.

“I joke that I chose a career where there’s no line for the bathroom,” says Kate Mitchell, co-founder of Scale Venture Partners, a venture-capital firm in the San Francisco Bay Area. Being the only woman on company boards potentially meant less influence on important issues, she found, unless she got creative.

“Decisions get made in the men’s room,” she says. “Do you follow them into the men’s room? Do you put your ear against the wall? Many times, it was easy to hear and so when they came out, I’d just start up the conversation” where they’d left off.

Tackling difficult subjects

Researchers at McKinsey and Lean In this year collected data at nearly 280 companies and surveyed 64,000 of their North American employees in one of the largest efforts ever to gauge the experiences of working women and men. As large as the share of women reporting harassment is, the report’s authors caution that the numbers don’t fully capture the experience of workers more vulnerable to certain types of misbehavior, such as those in service jobs, because most survey participants were white-collar employees.

Still, there are signs #MeToo is having an effect. Corporate hotlines have lit up since Hollywood mogul Harvey Weinstein became the first of dozens of powerful men to be toppled by harassment allegations last October. Convercent Inc., an ethics- and compliance-software firm that operates reporting hotlines and portals for more than 600 companies world-wide, says the number of harassment reports it took in over the past year jumped 72% from the 12 months before.

The Time’s Up Legal Defense Fund, an initiative launched by women in entertainment earlier this year, says it has received more than 3,500 requests for assistance with claims, most of them from low-income workers.

Meanwhile, harassment claims filed at the Equal Employment Opportunity Commission jumped 12% in the year ending Sept. 30 from the 12 months before.

#MeToo is also driving new efforts at some large companies.

Microsoft
Corp.

, Uber Technologies Inc. and Lyft Inc. have scrapped agreements that forced employees to resolve harassment claims in arbitration hearings rather than in open court.

After the departures of two fund managers accused of inappropriate behavior last year, Fidelity Investments created a response committee of Fidelity executives and an outside lawyer to give employees a new avenue to report concerns. Chief Executive Abigail Johnson moved her desk from the executive suite to the floor where key portfolio managers and traders sit.

Some companies say a big part of the solution lies in encouraging frank conversations and examining warning signs before bigger problems emerge.

“Every company has a policy around harassment,” says Beth Steinberg, who joined human-resources-tech firm Zenefits as chief people officer last year. “If that were sufficient, then Harvey Weinstein wouldn’t have happened.”

Zenefits went through its own workplace crisis nearly three years ago when it ran into insurance regulatory problems over its sales practices. In the aftermath, it brought in a new leadership team, laid off hundreds of staff and cracked down on a frat-house work culture by banning alcohol in the office.

More recently, it has periodically conducted an anonymous but detailed employee survey that lets the company discern if certain groups feel less supported than others, or other signs of discontent. Though the survey hasn’t specifically asked about harassment, the relative lack of women on tech teams surfaced as an issue in a few comments in last year’s initial survey.

One thing managers spotted and changed was that there wasn’t always a woman on the job-interview team. That could both discourage female applicants and contribute to biased hiring decisions, Ms. Steinberg says.

Over the next two quarters, the percentage of women in technical roles climbed to 24% from 9%. In the company’s Vancouver, British Columbia, office alone, the number of women jumped to nine from three.

“The whole feeling of that office has changed,” Ms. Steinberg says.

The company has also held a series of employee roundtables to discuss hot-button issues including harassment and to role-play various scenarios, such as hearing a co-worker make a disparaging remark about a woman.

To help get the conversation going, Ms. Steinberg told the group how, early in her career at another company, one of the most senior men cornered her in the copy room and groped her breast. Though she told her then-boss, they concluded the man held so much power that she would be better off not pressing the matter.

“I think back on it and still feel humiliated,” she says. At Zenefits, “we need to make sure employees know they have a voice.”

At Zenefits and other companies, such sessions have turned into forums where men and women talk through anxieties about interacting in a post-#MeToo world. “Some of the renegotiation of social boundaries is messy, and we have to be OK with this,” says Jennifer Allyn, diversity-strategy leader at PricewaterhouseCoopers LLP, which has held about a dozen of what it calls “respect in the workplace” discussions at PwC offices around the country since February.

At one discussion, a male partner asked whether he should begin taking a female client he frequently invites out to dinner to lunch instead to avoid any appearance of impropriety. The group arrived at a consensus: let the client decide.

The takeaway was, “Don’t immediately go to, ‘Let’s not have dinner,’ ” Ms. Allyn says. Another frequent question: whether hugging a colleague is still all right.

“The more space we make to talk about it—the unintended consequences, the backlash—the less fraught it has to feel,” Ms. Allyn says.

Yet the Lean In and McKinsey numbers suggest that there is more work to do. Only a quarter of women say incidents of harassment are rapidly addressed at their companies, compared with almost 40% of men. And nearly a third of women harbor doubts that reporting harassment to their employers would be helpful, or worry they would be penalized for speaking up—twice the share of men.

The disconnect between men and women extends to how they see efforts to even the gender playing field more broadly. While nearly 60% of men say gender diversity is a high priority at their companies, only 44% of women do. Men are also more likely to worry the diversity focus will make their workplaces less of a meritocracy. In fact, one in seven say they worry that being a man will make it harder for them to advance.

Women, particularly those of color, are less likely than men to say their bosses give them opportunities to grow, or praise their work to others. Substantive face time with senior leaders is a key way both men and women find sponsors who will champion them for promotions, Lean In and McKinsey found, yet fewer women are having those kinds of interactions with higher-ups. That’s even more so the case for black women.

Plans for inclusion

In September,

American Express
Co.

began rolling out training for leaders at all levels in the ways that managers can build inclusive teams, particularly for women and minorities that report to them. That could include efforts as small as highlighting a point a woman made in a meeting if someone interrupts her, or, if a colleague repeats her idea without giving her credit, pointing out that she raised it first, says Sonia Cargan, American Express’s chief diversity officer. About 1,300 managers at the vice-president level and above will go through the training this year, followed by thousands more midlevel managers in 2019.

At Milwaukee-based Northwestern Mutual Life Insurance Co., part of senior leaders’ jobs is to create succession plans for their positions, and each has to include at least one woman and a person with a minority background. That motivates bosses to make sure those candidates get the experience and support they need to be viable potential successors, says Chief Executive John Schlifske. The same applies to him for whenever he eventually departs.

“My board has said that the candidates for my job have to include women, and they do,” he says. The push, he says, has helped to boost the percentage of female senior leaders to 41% from 21% five years ago.

In the past, “everything we did was a program, this thing on diversity or this thing on unconscious-bias training,” Mr. Schlifske says. “I don’t think those are bad, but I just never saw those work if you didn’t add something in the workplace that was more day-to-day kind of stuff.”

Ms. Fuhrmans is The Wall Street Journal’s deputy bureau chief for management in New York. Email vanessa.fuhrmans@wsj.com. Chip Cutter and Lauren Weber, Journal reporters in New York, contributed to this article.