There is a plethora of concept inventories available for faculty to use, but it is not always clear exactly why you would use these tests, or how you should administer them and interpret the results. These research-based tests about physics and astronomy concepts are valuable because they allow for standardized comparisons among institutions, instructors, or over time. In order for these comparisons to be meaningful, you should use best practices for administering the tests. In interviews with 24 physics faculty, we have identified common questions that faculty members have about concept inventories. We have written this article to address common questions from these interviews and provide a summary of best practices for administering concept inventories.