Pay transparency is a hot topic for today’s start-ups, with some entrepreneurs arguing that it fosters healthier workplaces and fairer compensation. But what if you’re one of the vast majority of people who doesn’t work in such an open office? There are still ways to gauge how much your cubemates are getting paid—and whether it’s time to ask for a raise.

The key is to be strategic in how you get the info, says Connie Thanasoulis-Cerrachio, a career coach and cofounder of SixFigureStart. “You must be careful because management never wants you to ask, and it can look unprofessional when this information bubbles to top management,” she says. Rather than accost folks at the water cooler, try sleuthing out salary info this way:

1. YOUR ALMA MATER

“Even if it’s been years since you graduated, your university can be a good source of information for you,” says Thanasoulis-Cerrachio. That’s because many college career offices survey alumni about salary info and also compile industry data. Get in touch with a career counselor to get ahold of those stats: If alumni work at your organization, you may get company-specific details, but even if you’re the lone alum at your company you can get a snapshot of what people make in your industry.

2. THE HR DEPARTMENT

In general, the smaller the company, the more likely HR is to be reticent about revealing what certain positions pay. (When the graphic design department is just one person, connecting the dots isn’t too hard.) “But if you work for a large company, you can always ask someone in HR to give you the salary ranges for different positions,” says Thanasoulis-Cerrachio.

And at some companies, compensation is a cut-and-dry formula, and sharing those salary levels isn’t taboo. “Of course, the friendlier you are when you ask, the better,” she says. “It’s always helpful to make a friend in HR!”

3. PUBLIC RECORDS

Private companies are typically tight-lipped about salary info. But if you work for the federal government, those pay grades are published by the U.S. Office of Personnel Management. If you’re at a not-for-profit, you can sleuth out salaries for high-level employees by peeking at the organization’s tax returns (form 990). Start with GuideStar, which has info on thousands of not-for-profits. Don’t think the info is only limited to the director, either: The IRS requires nonprofits to share salary details about its officers, directors, key employees, and the five highest-compensated employees making more than $50,000. In a smaller nonprofit, that might mean details on most of the staff.

4. PAY SITES

Glassdoor.com is the go-to for most salary sleuths, but it’s not the only resource. Thanasoulis-Cerrachio recommends also checking out Payscale.com, GetRaised.com, Vault.com and Wetfeet.com. “People are very willing to share, because it’s so anonymous,” she says. Just keep in mind that the info may skew toward forward employees, so casting a wide net across multiple sites will give you more data points to compare.

5. JOB LISTINGS

Odds are, you aren’t scouring your company’s help wanted ads. But if you’re curious about compensation, you’re missing a big opportunity for clues. Many listings will include a salary range, and if the company is hiring in your department or for a similar position, that’s a good indicator of what your coworkers are probably earning.

6. YOUR COWORKERS

Yes, talking about salary is still taboo in most offices, but that doesn’t mean you can’t query a trustworthy coworker. “Don’t ask someone you barely know or you’ll look very unprofessional,” says Thanasoulis-Cerrachio. “Instead, trust your gut about who you can ask directly.” She recommends acknowledging that salary isn’t typical office chatter, but then plunging ahead anyway: “You could say something like: ‘We’re not supposed to talk about compensation, but do you think we could share with each other what our base is or give a range?’” If the coworker bristles, drop it, of course. And if you do get the info, be ready to share your own salary in exchange.