Q: I just found out my predecessor made more than me. My boss doesn’t know I know. What should I do? A: Before you work yourself up into a fury, keep in mind that “it’s unusual for someone to come into a role and make the same exact salary as the previous person in the job,” says Lydia Frank, editorial director at compensation data provider PayScale.com. Also, there may be a good reason that you make less. Many factors affect compensation. Employers typically stick within a general range for each position, and where you fall within that range depends a lot on what you bring to the table–your years of experience, your unique skill set and your education. Unless those attributes are identical to those of your predecessor, you shouldn’t necessarily expect to command the same salary. Additionally, as unfair as this may seem, the economy may play a role: The person you replaced may simply have been hired during more flush times at your company. If after having weighed these factors you still see an imbalance, however, you should talk to your boss. But you’ll want to be careful about how you do it, as it can be a delicate dance to get your boss to see your side. (It’s been widely reported that one of the factors in the recent high-profile ouster of New York Times executive editor Jill Abramson was her complaints about earning less than the person she replaced.) First, get some data behind you, since you want to avoid bringing up what you know about your predecessor’s pay. By mentioning that, “You’d be putting your boss on the defensive,” says Frank. “That’s not a conversation that’s likely to go well.” There are several ways to find out what’s an appropriate income for your position. You can check salary sites, such as PayScale.com which crowd sources data on compensation, and Glassdoor.com, which posts company salary reports. You can also turn to your network and ask current or former colleagues for insight. (While it’s still taboo to talk about pay, it may be easier if you ask about a range.) Then tell your manager that you’ve done some research on salaries in your position, and the data you’ve found indicates that you’re are at the low-end of the scale. From there, build your case about why you are a top performer and should earn more, using quantifiable examples of your successes and highlighting wins that align with your boss’s and the company’s goals. If your supervisor pushes back, ask what you can do to get to that next level: Get more training, add a particular skill or hit a sales target? The bottom line: When it comes to your salary, what’s most relevant is whether you are making what you should based on the current market price for your position and your qualifications, not what the person before you earned.