Of course you'd like to have a job and a life. But before you ask your boss about flextime, there are a few things she wishes you knew.

Eleven years ago, stuck aboard a bouncing little commuter jet, circling Boston in a gusty snowstorm that would not let up, I found myself cursing my fancy job as a consultant, my hard-driving boss, and my crazy, unmanageable life. Plus I was sobbing. My daughter's Christmas play started in 15 minutes and I had promised I absolutely, positively would not miss it. I missed it.

A few months later, I quit. I had found a publishing company where my new boss told me I could not only travel less, I could work at home two days a week. When I started, I discovered dozens of colleagues like me, holding it together at home and on the job thanks to flextime. Almost every kind of arrangement seemed okay with our boss—as long as we delivered results.

Filled with relief and gratitude, we did. For many of us, flextime made both a healthy family situation and a meaningful work experience possible at once. It was a lifesaver.

That's why, when I was promoted a few years later, I was determined to follow my boss's example. With my help, I vowed, parents would find that elusive balance between kids and work; adult children would be able to care for their elderly relatives with less stress. And everyone would be happy.

Except, in pretty short order, I wasn't. Within weeks the flextime I had so loved as an employee had become a throbbing headache for me as a boss—with its tangled-up logistics, lowered productivity, and contentious employee relationships. (Who knew non-flextime users could resent their flextime colleagues so bitterly?)

Still, I kept my mouth shut. I knew flextime had to exist or I'd lose good people. I also didn't want to sound like the hypocrite I'd become. But most of all, I was silent because I thought I was alone in my struggle. I wasn't—not by a mile.

Over the past four years, my husband, Jack, and I have spoken with thousands of bosses caught in that same bind. They get the virtues of nontraditional scheduling but grapple with its implementation. Recently, we codified our research, and the result is a four-point list of tacit truths about flextime—from the boss's point of view.