Co-written with Katherine Ullman.

"My small contribution to feminism is leaving the office at 5:15 PM three times a week to pick up my daughter...and not hiding it." You might expect that these are the words of a working mother who, after too little sleep and too many people wondering "how she does it," decided to draw a line in the sand for all to see, with work firmly on one side and family on the other.

But you'd be wrong--we heard this from a young professional father. And who could blame you for your guess? With all of this recent hullabaloo about female breadwinners (elegantly complicated here and here ), it's easy to overlook the small ways in which working fathers' lives are changing, too--or to even consider their evolving role in the work-life frontier at all.

To put this young attorney's "contribution" in context, 5:15 PM is considered early in the day at most firms, his included. Half of young lawyers report working 50 hours a week or more. In the professional world in general, 40% of men report the same. That's a 10 hour work day, at minimum.

But despite the expectation that men work grueling hours, fathers are spending more time during the week with their children than they did in the past, and millennial fathers are doing this today more than older fathers, suggesting a lasting change. With extreme expectations at work and a growing desire to be home, no wonder fathers report higher levels of work-life conflict than others.

Let's dig further. Although one experimental study found that simply being a father actually helps men's careers, another study found that when fathers let family interfere with work, they suffer even greater work penalties than their female counterparts. And nothing reveals a father's family responsibilities more than leaving the office early, taking advantage of flexible work arrangements, or using family leave.

In a new special issue of the Journal of Social Issues, co-edited by Joan, the co-author of this post, and colleagues Jennifer Glass, Shelley Correll, and Jennifer L. Berdahl, several studies explore exactly why men experience such stigma when using family-friendly policies.

One study found that men and women are equally likely to want a flexible schedule but men were much less likely to plan to request one. Many men feared that asking for a flexible schedule would make them seem more feminine. And those who actually did ask for it were likely to ask for less than they really wanted.

A second study sheds light on what's at stake for these men. Participants in the study were asked to rate men and women who took family leaves and those who did not. If the employee was a man who took time off, he was less likely than other men to be recommended for promotions, raises or high-profile assignments. Why? These men were seen to have traditionally feminine traits, which in turn, made them seem like bad workers. The flexibility stigma, in other words, is a femininity stigma.

It makes perfect sense, then, that a separate study found that men in male-dominated workplaces who did more child-care received more "masculinity harassment" (disparaging remarks about one's masculinity) than other employees.

So where does this leave fathers? Let's go back to our young attorney. He explained to us that by intentionally talking to colleagues about leaving early, he hoped break down the stigma surrounding family responsibilities; this, he hoped, would benefit both men and women at his firm and, by extension, their partners. Still, as the current breadwinner of his family, he's only willing to take this so far: "I am fine with leaving at 5:15 three days a week, but am I willing to risk my job by trying to be the first male at my firm to work part-time in order to be at home with my kids? Maybe not."

This young man is an exceptional guy, we'll grant you, but if even he is scared to use a part-time policy, there's little hope of many other fathers making the changes they want for themselves and their family.

In continued celebration of Father's Day, let's remember that women can't "lean in" until men share the care, and men won't do this until workplaces adopt family-friendly policies and tackle the flexibility stigma that renders them impotent.