I’m continually amazed by the extent to which we expect other people to read our minds. It happens in relationships (“my husband should have known I wanted flowers”) and in families (“my mother should have realized it didn’t want her to say that”)—and it happens all the time at work: “I can’t believe my employee/colleague/boss didn’t do that—s/he should have known it was important!”

Think about it—how many times over the past few months have you felt irritated at work because people did something you thought they shouldn’t have done, or didn’t do something you thought they should have? I’m not talking about someone failing to fulfill a stated commitment, but something that you thought they just should have known. My italics are intentional: that phrase is the heart of the mind-reading we expect from other people.

Here’s an example. Recently I was talking to a fairly senior executive who had hired a really bright young man, a new college graduate, to be her departmental assistant. She was complaining about his “attitude of entitlement,” as she put it, and then she went on to say that she saw this trait in all the Millennial employees she knew, and found it disturbing and irritating.

I asked her what, exactly, he was doing that she saw as “entitlement” behavior.

“Well,” she said, “He talked back to the CEO in a meeting recently—just flat-out disagreed with him. And he never volunteers to help others with their projects when they’re under the gun and he doesn’t have as much to do.”

“How would he know those things aren’t OK to do?” I asked.

She looked puzzled. ”What do you mean?”

“I mean, who would have told him that it’s not cool for junior people to push back on the CEO in public at your company? And how would he know that he’s supposed to pitch in on others’ work?”

“But, but…,” she sputtered, now looking a little irritated at me, ”Everybody knows those things.”

As we continued to talk, it became clear that she thought he actually knew the rules, but was simply choosing to flaunt them—thus her “entitlement” assumption. It took a longer conversation for her to start to see that her employee would not necessarily have learned either of those things at college (where you’re expected to argue with your professors, and you pretty much just do your own studying).

I’m convinced that a great deal of the irritation, impatience, and disappointment we feel about those around us arises because we assume they “should” know things that they simply don’t know.

Fortunately for you, I have a solution. Whenever it’s really important to you that someone else behave in a certain way, make a clear and explicit agreement with them about it. Instead of thinking they should already know they need to do it, or hoping they’ll do it, or getting upset when they don’t do it—make sure they know what you want them to do, and why, and then simply ask them to do it. It’s particularly important that you take this approach with employees—and especially employees who are different from you (for instance, culturally, ethnically, or generationally)—those folks are likely to have even fewer core beliefs in common with you about “correct” or “appropriate” behavior.

Here’s a simple three-step approach to making this kind of clear mutual agreement with your employees (it actually works equally well with peers—and getting clear agreements with peers is increasingly important in today’s flatter, more matrixed organizations):

Clarify: First, work with your employee to create a clear and compelling mental picture for him or her of what needs to be done, describing the task or responsibility in specific, measurable terms and providing as much detail as is appropriate. Make sure the employee knows why this behavior is important to the company, to him or her, and to you. Once you feel you’ve communicated clearly, listen and ask questions to make sure the employee understands what you’re asking for, and is willing to do it. In the example above, this might sound like, “Joe, I realized I haven’t talked with you about the expectations around sharing workloads in our company. Generally, when someone on the team is swamped, and you have free time, you’re expected to offer to help. Because our work ebbs and flows, we’ve realized it’s a great, informal way to manage the workload—and it has the added benefits of making sure that we all keep learning new things, and can cover for each other when we’re out. So, what do you think—does that make sense?”

Finally, make sure the agreement is doable: that the employee has the necessary skills, knowledge and resources (or can get them), and that any other obstacles to fulfilling the agreement can be overcome. For example, the employee in this situation might say, “I’m not sure I’ll know when someone needs help.” Great point. You might respond, “Well, I think you’ll get a feel for it as you work here longer and get used to how people operate, but for now, why don’t you check in with me whenever your workload is light, and I can let you know if someone else on the team could use your help.”

Commit: In this second step, you make sure that you and the employee understand each other, are agreeing to the same thing, and will have some way of checking to see whether the agreement is working. A great way to do this is by asking the employee to summarize his or her understanding of what you’ve agreed to do, then setting benchmarks (to check how the agreed-upon work is proceeding) and any necessary deadlines. For example, in the situation we’ve been discussing, you might say something like, “OK, just so I know you and I are on the same page, what’s your understanding of what we’ve agreed to here?” Once the employee summarizes (in this case, that might be as simple as, “You’ve asked that I make myself available to help others on the team with their work when I have time—and I’ll check in with you to see who might need the help,”) you might say, “Yes, that’s my understanding, too—let’s touch base on this at our weekly one-on-ones for the next few weeks to see how it’s going.”

Support: No matter how clearly and well you and your employee move through the first two steps, without this third step it’s unlikely the agreement will be kept—or at least unlikely that it will be kept consistently and well. This step is what happens after the agreement-making conversation above. Supporting an agreement means that you and the employee both honor whatever commitments you’ve made. You also provide feedback about how the employee is doing relative to the agreed-upon behavior. In the example we’ve been using, for instance, it would be great just to say to your employee something like, “When you came to me on Thursday to let me know you had some availability, that was great. Sally really appreciated your help—it allowed her to meet the client’s deadline on her project.”

It’s amazing how relatively simple and quick it is to make these kinds of agreements. It generally requires 10-15 minutes of thinking through ahead of time how you’ll explain the what and why of what you’d like from the other person; 10-20 minutes for the “clarify” and “commit” conversation; and then little bits of time after that to support the agreement. Less than an hour invested to save yourself (potentially) many hours of misunderstanding, inefficiency, frustration and ill will, and to hugely increase the odds that the things you need your employees to do will actually happen. And if that’s not enough good stuff: having more clarity about what they’re supposed to do and why will give your employees a much better shot at success.

Oh, did I mention this also works with your spouse? I’m just sayin…