Once you have put a job candidate through a first or second interview and you have a strong indication that he or she could be a good choice for the job, it is time to begin checking references. It is important to understand that referencing is not asking for an endorsement of the candidate. Rather, you are seeking clarification and confirmation on what you have learned from the resume and interviews, and you are filling in any blanks. While it may seem like a lot of work, especially if you are doing reference checks for several candidates for one job, it will help distinguish the candidates and reduce question marks about the candidate you ultimately choose.
I begin the reference check by calling the candidate to report that I am interested in pursuing the work relationship and to ask for references, ideally in a 360-degree fashion (one or two bosses,...