Lean In – Think this doesn’t matter to you? Think again.

Childcare costs more than college. Mothers withequal resumes are hired 80 percent less of the time than non-mothers and are offered lower starting salaries. It costs over $200,000 to raise one child from birth to age 18 (not including college).

All of this is happening every day in the backdrop of a national a “Lean In” conversation.

Let’s face it. Whether you love or hate Sheryl Sandberg’s premise in her new book, “Lean In,” which analyzes why women have stalled in workplace leadership and suggests ways to advance; this book is shining a spotlight on a long overdue conversation about the roots of gender-based inequality in the workplace.

We have avoided the conversation about the reality of women, and importantly of mothers, in the workforce for too long, which is particularly odd given that women comprise half of the entire paid labor force for the first time in history, three-quarters of moms are now in the labor force, and most families now need two breadwinners to make ends meet.

Yet despite comprising half of the paid labor force, only 5% of Fortune 500 CEOs are women. The glass ceiling remains solid and a Maternal Wall is blocking the way for many women to even get anywhere near that glass barrier. Yes, a Maternal Wall.

Here’s what the Maternal Wall looks like: Women without children make 90 cents to a man’s dollar, mothers make 73 cents, single moms make about 60 cents to a man’s dollar, and women of color experience increased wage hits on top of that. (Overall women make only 77 cents to a man’s dollar for full-time year round work) More than 80% of women in our nation have children by the time they’re forty-four–and most hit that wall.

Think this doesn’t matter to you, or to our national economy? Consider this: Women make three-quarters of purchasing decisions. When women don’t have adequate funds in their pockets, our entire economy — which for better or worse is now built on consumer spending — suffers.

The glass ceiling and Maternal Wall not only hurts women’s pocketbooks, they also hurt the bottom line of our nation’s businesses. A 19-year Pepperdine University survey of Fortune 500 companies found that those with the best record of promoting women outperformed the competition by anywhere from 41 to 116 percent. In other words, more women in leadership meant higher profits.

At MomsRising.org, an organization of more than a million members nationwide, we know our economy will be stronger when more women and mothers are in leadership, as well as when more women are paid fairly and can use their purchasing power in local communities. Because of this, we value women like Sheryl Sandburg who encourage and mentor other women to lead. (Check out the vibrant conversation about this here.)

We also know that many women and mothers are struggling against tradition, subliminal discrimination, and structural barriers. It’s going to take more than each individual “Leaning In” to make the changes we need. Indeed, we need to start “Leaning Together” and lifting each other up.

A lot of the media discussion around Sandberg’s new book has been focused on women in higher level positions. But let’s face it: This leaves many women out. In fact, it leaves most women out.

Only 9 percent of all women in the labor force earn $75,000 or more annually, 37 percent earn between $30,000 and $74,999 annually, and 54 percent earn less than $30,000 annually.

We are living in more than one America.

The realities of life for higher-wage earning women are vastly different from the realities of most women in our country. While one group is engaged in the conversation about how to best “Lean In” to fight for six figures or more and a corner office, more than 80 percent of low wage workers don’t have access to a single paid sick day for themselves or their children.

There are vastly more women in low wage positions than in high. In fact, the majority of minimum wage earners are women.

And this is the crux of the controversy.

While an honest and soul searching discussion about why highly paid women are not advancing to the top of organizations is essential, we must also have an equally serious conversation about how we will advance workplace policies like paid sick leave and paid family leave that are essential to the economic security of all women and their families.

Having access to such workplace policies is shown to help lower the wage gaps between moms and non-moms, save taxpayers money in the long run, as well as raise all boats by benefiting businesses and all employees. For instance, in states with paid family leave, a recent study found that women who take paid leave are 40% less likely to need or receive food stamps in the year following a child’s birth when compared to those who do not take any leave. Yet too few people have access to these workplace policies.

In short, our national “floor” for workplace policies is way too low. These floors need to be raised; structural barriers need to be addressed.

As we applaud those who “Lean In” to advance their careers, we must not forget that other women will need more than assertiveness and self-promotion to advance. Most mothers in the low wage workforce are struggling to find quality and affordable daycare (which now costs more than collegein most states), and are working in jobs without paid family leave, sick days, or flexible work options that ensure that employees can be successful both at home and at work. Middle income women struggle with many of these same work structure issues, while women in higher income positions often have access to these programs.

We’ve seen recently, that the mere ascension of women in the workplace alone does not guarantee that family friendly policies will be implemented. For instance, Yahoo CEO Marissa Mayer’s move to end the company’s policy of allowing employees to work remotely.

Leaning in is a necessity, but it’s going to take more than “leaning in” to advance all women in the workforce. And in fairness, Sheryl Sandburg acknowledges this in her book.

Solutions are within our reach.

We know which policies (like paid family leave, earned sick days, and affordable childcare) save taxpayer dollars, improve women’s economic security, act to help close gender-based wage gapsand break down the Maternal Wall, and strengthen our national economy as a whole. To be blunt, when we don’t lean together, we’re leaving money on the table.

These solutions won’t magically happen without people coming together to push to update our outdated workplace policies, practices, and laws. It’s going to take all of us–women, men, elected and corporate leaders–leaning forward together to build a nation where women, families, and businesses can thrive.