Hiring managers often struggle to come up with the right set of questions to ask when they conduct interviews. An article I recently read on Inc.com points out that, "More than 90 percent of hiring managers think they're good interviewers, yet rarely do they reach unanimous hiring decisions with other 90 percenters in the same room evaluating the same candidate." So, Lou Adler, a seasoned human resources consultant and author of The Essential Guide for Hiring & Getting Hired, set out to find the essential interview question that could help solve this problem.After a decade "of trial and error," Adler finally determined the essential interview question ─ "What single project or task would you consider your most significant accomplishment in your career to date?"According to Adler, it is not just the question itself that is important, it's that the question effectively sets up an opportunity to ask relevant follow-up questions that can provide valuable insight about the candidate. Hiring managers can gain a thorough understanding of the candidate's accomplishment and its impact, challenges the candidate faced and how they responded to them, mistakes the candidate made and how they would do it differently next time, and what they enjoyed most throughout the process.After 36 years in the industry, Adler finds that asking this one question in an interview is the single best strategy to help hiring managers quickly and unanimously determine whether a candidate is the right person for the job. Adler concludes that, "After you hire a few people this way, you'll also call it the most important interview question of all time." This is a bold statement but perhaps worth a shot. Ask the question and decide for yourself.