When asked about our proudest business accomplishment, the answer is always “Us!”—the friendship we’ve nurtured and the successful partnership it’s fostered through Of a Kind, the fashion e-commerce business we founded together in 2010. What we’ve realized in taking a closer look at the ways in which our relationship functions is that our professional partnership has been the beneficiary of the tenets that anchor female friendship: emotional intimacy, vulnerability, a penchant for collaboration, and a pattern of mutual support—qualities that have unique power and potential to spawn great ideas and create foundations for strong businesses.

In making the transition from friends to business partners all those years ago, we knew we were signing up for a much more complex relationship than when we met as undergrads at the University of Chicago. We went from seeing each other weekly to spending more time together than we did sleeping. Finances became a constant topic of conversation, and not just in the context of whether one of us was feeling too broke for a dinner date. We spent our nights, weekends, and soon 9-to-5s each making decisions that would affect the other. Our careers and our futures became intertwined.

Though this transformation felt natural to us—how else would someone do something as scary as start a business other than with a close friend by their side?—we encountered plenty of people whose eyes popped out of their heads when we told them we were taking our personal relationship professional. Oh, the horror stories! The whole plot of The Social Network! Sure, we recognized that in pursuing this at all, we could be putting our friendship on the line. But our shared history brought us immense, intense comfort—a much-sought-after feeling during the constant turbulence and uncertainty that come with building something from the ground up.

We also walked into this knowing we saw each other as equals; there was no power dynamic to contend with, and we trusted that would remain a constant. At some point, after enough soul-crushing investor meetings and awkward interviews with job candidates, the looming sense that we could walk out of this venture short a business and a bud faded away. Once we’d put enough hours, years, and life into Of a Kind, it was clear that if something didn’t work out with the business, our relationship would survive, just as it had plenty of other lows. We were in this together, even if “this” ceased to exist.

Sign up: Click here to subscribe to the Broadsheet, Fortune’s daily newsletter on the world’s most powerful women.

Though a certain—mostly male—breed of human loves to pit women against one another, as if every female duo is Brenda and Kelly on the matching-formal dress episode of Beverly Hills 90210, proving those people wrong—both in friendship and in business—has been a career highlight. We are hardly the only women who’ve found something appealing about pairing up: While prepping to have new headshots taken, as we do and dread annually, we turned to the internet for inspiration/instruction on how to pose without looking like Mary-Kate and Ashley Olsen on the poster for Two of a Kind: How to Flunk Your First Date. It was there, in our Google Images search results, that we realized how many of the new ventures taking over the world were run by pairs of women: Elizabeth Cutler & Julie Rice of SoulCycle (who, in photos, benefit unfairly from the use of bikes as props), Betsy Beers & Shonda Rhimes of Shondaland (who have taken the Olsen approach), Phoebe Robinson & Jessica Williams of 2 Dope Queens (who excel at giving don’t-mess-with-us face), Dr. Katie Rodan & Dr. Kathy Fields of Rodan + Fields (who love a crossed-arm power pose).

Whereas 10 years prior our vision board of high-profile business partnerships likely would have been littered with awkward snapshots of men who’d monopolized the space—Jobs and Wozniak, Gates and Allen, Procter and Gamble, Ben and Jerry—we now had plenty of female icons to reference. This shift isn’t a coincidence—it’s a direct consequence of an evolving business environment. Slow but steady progress toward dismantling male dominance at the office has carved out space for women to collaborate instead of compete professionally, and that’s set the stage for change.

Duos and trios of women who have partnered in leadership positions are paving the way for a reimagined workplace that leads with qualities like compassion, mutual support, and transparency. They’re implementing long-view practices that result in strong business outcomes. These partnerships are changing not just what it means to be women in the workplace, but the workplace as a whole.

This evolution in the business world coincides, unsurprisingly, with a long-overdue cultural shift that recognizes that female friendships aren’t all about backstabbing and cattiness. The Mean Girls narrative got hit by a bus and in its wake came #squadgoals and Shine Theory. Naturally, this ethos also holds true for friendships at the office.

“Work wife,” a term spawned from “office wife”— which itself dates back to the 1930s, when it was used by men to describe an especially high-functioning secretary—has more recently been co-opted to describe a combination of personal and professional bondedness and healthy, supportive closeness among women. It’s a dynamic that requires an in-this-together attitude and approach that’s viable in any business setting with right-minded people, and in our experience, it’s a game-changing one.

Excerpt from WORK WIFE by Erica Cerulo and Claire Mazur, copyright © 2019 by Erica Cerulo and Claire Mazur. Used by permission of Ballantine Books, an imprint of Random House Publishing Group, a division of Penguin Random House LLC. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.