Let’s admit it. We all slip up occasionally. Maybe we don’t respond promptly to every e-mail message, or we swear under our breath from time to time. But we’re doing OK, right? Do we really need to worry about the finer points of correct behavior?

Let me answer that question with a polite “Yes.”

In an age when offices have given way to cubicles, when electronic devices keep us in constant communication, and when the boundaries between our professional and personal lives are dissolving, we need the rules of etiquette more than ever. Etiquette, after all, is just a code of conduct that allows us to live and work together with relative ease, fosters good relationships, and reduces the social frictions that impede our happiness and even our professional success. As Peggy Post and Peter Post argue in their update to Emily Post’s The Etiquette Advantage in Business, “Knowing how to behave in a wide variety of professional settings not only makes you a more pleasant, confident, and enjoyable person to work with; it also provides you with all-important tools…that will help propel you and your company toward your mutual goals.” Or, as Judith Martin puts it tartly in her recent Miss Manners Minds Your Business (coauthored with her son, Nicholas Ivor Martin), we’re all fumbling with a “wider cultural confusion that has left the workplace riddled with etiquette land mines. Whether you blame resistance to relaxing the old rigidity of behavior or ignorance of traditional businesslike behavior, everybody…seems to be getting on everybody else’s nerves.”

Indeed, social mores are changing so quickly and home and office becoming so intertwined that even the most mannerly are probably confused. Thus the staying power of the etiquette advice genre (Erasmus put out a book on good manners for boys in 1530—no fidgeting, no scratching), the ongoing popularity of trusted authorities such as Miss Manners and Emily Post (via her great-grandson and his wife), and the rise of such relative newcomers as Slate’s Dear Prudence, the Financial Times’s Dear Lucy, and the New York Times’s “Social Q’s” column.

Consider: Should a female manager stand to shake hands with a younger male associate? Miss Manners instructs us to factor in age, rank, and venue. The core rules still apply generally: Women don’t rise for men, older people don’t rise for younger ones, and higher-ranking people don’t rise for those of lower rank. But if you’re an older, higher-ranking woman, and you’re meeting in your office, then you should stand to shake hands—as a sort of “hostess.” However, Miss Manners nods to evolving notions of gender roles, allowing that someone’s sex is the least important factor in an office setting.

“When attempting to enter the business world, you need to learn to be someone else. It is called having a professional identity.”

Got it. But how do you deal with the petty annoyances of the modern workplace? What do you do when the colleague in the neighboring cubicle breaks out a smelly lunch? When people bellow into their cell phones? When your boss fails to respond to your e-mail? When a prospective employer doesn’t acknowledge receiving your résumé? The rules of work are changing. Does that mean that the basics of good manners are changing, too?

Emphatically not. The Posts put it simply: Good business etiquette “is not a set of ironclad ‘rules.’ In fact, most of what people call business etiquette is really little more than common sense driven by being considerate, respectful, and honest with others in your business life.” The Martins draw a helpful distinction: Manners are “the principles of courteous behavior” and etiquette “the rules that apply to a particular situation.” So manners don’t change, but etiquette evolves. Once you understand that, you can pretty much figure out the rest.

If you read these two books, you’ll learn that it’s not smart to criticize the boss’s attire, that you shouldn’t use speakerphone unless you’re behind closed doors, and that there are inoffensive ways to let your cubicle mate know he talks too loudly on the phone or that her fish dish is “distracting.” You’ll find the answer to the question “to prairie-dog or not to prairie-dog?”: The cultural norms in your office determine whether it’s OK to pop up to look over your cubicle wall into your neighbor’s space.

I was surprised by a couple of points. According to Miss Manners, “Unsavory as conducting business by phone from the bathroom may be, it doesn’t violate etiquette.” Noted. And the next time you’re stuck in the Escherian nightmare of an automated phone tree, you can break free by dropping a loud F-bomb, as one “gentle reader” did, whereupon he was finally delivered to a live customer service representative. Miss Manners didn’t approve—but great tip!

The Posts’ encyclopedic guide is the more practical of the two books, addressing the résumé question, for example, while Miss Manners glosses over it. And the Posts are particularly good at walking through the protocols of job hunting and answering such touchy questions as what to say when a colleague is seriously ill, miscarries, or divorces.

If you, like me, read etiquette advice as sociology, however, you’ll prefer Miss Manners’s witty, though sometimes random, guide. Here’s one gem: “My new boyfriend was recently released from our company,” writes a hapless correspondent. “My company picnic is coming up and I would like to ask him to go….I am afraid this would be awkward. Any advice?” Miss Manners’s response: “Spare him.”

Both the Martins and the Posts are careful not to overreach. For example, Miss Manners defends those infuriating phone trees in response to a reader’s complaints. They can be annoying; they can also be helpful. But in and of themselves, she writes, they are not rude.

To be sure, there are many “etiquette experts” out there, with sometimes questionable authority. I’m still puzzling over a recent Forbes column decreeing that one shouldn’t check e-mail while riding in an elevator. Why not? As Miss Manners would remind us, business etiquette exists “to maintain personal dignity and to show respect for others…; to maintain a pleasant demeanor without invading others’ privacy; to balance competitiveness with cooperation; to take responsibility but remain flexible; to be both attentive and discreet; and to combine honesty and tact.” Etiquette lays out the rules of sensible living. It helps us be less annoying and, to be venal about it, get what we want. It can save us from the quotidian nuisances of office life. Most important, it allows us to redraw the boundaries that define civility and ensure our own sanity.