Fortune last month published its 2019 list of the largest 500 US companies based on total revenues. It reported that 33 of those firms have female CEOs — the highest ever number. Still, that means that women account for the top leadership job in only 6.6 percent of the largest US firms. The 2019 figure of 33 female CEOs is up significantly from last year’s count of 24, but their numbers remain so small that the departure of just a handful from their roles would significantly decrease the overall ratio — if they are not replaced by women, which they very seldom are. Globally, women are making some progress in management positions, but the progress is slow. The worldwide firm Grant Thornton provides annual data on the number of women in management positions — C-suite jobs, partners and managing directors — in multiple countries. Their latest report, released in March, found “the highest percentage of women in senior management on record at 29 percent,” a 5 percent increase over 2018. However, their reports have seen only a 10 percent increase since 2004, when the number stood at 19 percent. Furthermore, women in senior management positions are largely confined to human resources director (43 percent) and chief finance officer (34 percent). These data points raise questions about why, despite some improvements, women remain significantly underrepresented and why progress is not happening faster. There are several possible drivers of progress so far. Several experts have pointed to increasingly diverse boards, noting that boards with more women on them are more likely to appoint women as CEOs. Many business leaders are increasingly aware that more diverse leadership teams bring a broader array of experiences and tend to make better business decisions. Evidence cited in the Harvard Business Review and elsewhere has demonstrated that leadership teams that include women often lead to better business results than exclusively male teams. Diverse leadership teams also better reflect a company’s customer and client base, bring in more diverse perspectives that are better at identifying risks and opportunities, can provide a broader ethical perspective, and are more likely to produce innovative ideas. In some countries, particularly in Europe, government efforts designed to reach targets for a certain percentage of women on boards may be helping.However, there are many factors that are holding women back from reaching senior management positions. One constraint is the smaller pool of women managers to draw on. A recent Associated Press article noted that, in the US, men and women tend to enter companies in similar numbers, but the number of women declines further up the management ladder. In her well-known 2013 book, “Lean In,” Facebook’s chief operating officer Sheryl Sandberg noted that she watched many women fall off the management ladder. It has been widely assumed that, as more women enter business, the pipeline of future senior management positions would be extended. But a 2017 article in the Harvard Business Review reported that this assumption has not panned out. There are many reasons why women are less likely than men to rise through middle management positions into senior positions. While the reasons vary somewhat between countries, they apply in many parts of the world. Overt and implicit bias against women — even unconscious bias held by well-meaning men and women — is a major problem. Multiple studies have demonstrated challenges, such as people seeing men who are confident and assertive as natural leaders while the same qualities make women less likeable. Men who ask for promotions and salary increases are more likely to be seen positively, while women who ask for the same are more likely to be viewed negatively. In meetings, people are more likely to call on and listen to men than women. In addition to various forms of bias and discrimination, there are factors that can prevent women from moving progressively into more senior leadership positions. Lack of mentorship is an oft-cited problem. The responsibilities of caring for children and elderly family members are much more likely to fall on women, especially in countries that lack forms of support such as paid maternity leave, but also in countries with policies to assist working mothers. To some extent, women may also have different perspectives on life priorities and how to balance work and life, which can hurt them in work environments that privilege how many hours employees work over other metrics.Interestingly, some women respond to glass ceilings in companies, a lack of flexible hours and bias by leaving traditional workplaces to become entrepreneurs. But female entrepreneurs also face challenges; for example, research published in 2018 in the Academy of Management Journal demonstrated that venture capitalists tend to ask male and female entrepreneurs different questions in ways that privilege men. Despite this, entrepreneurship can offer women greater flexibility and an opportunity to lead their own business rather than fighting to move up a traditional management structure. Wise investors and employers will seek to increase diversity, including greater gender parity in senior management and on boards. However, expecting women to conform to male-dominated structures will lead to only limited progress. The exciting trends to watch are women creating their own businesses or reshaping existing ones to improve the working environment for all employees and to produce business decisions that reflect a wider range of experiences.