Over the past 20 years, we’ve been perplexed as to why executive hiring fails approximately 50% of the time. Why do so many executives fail to hit the target consistently and live up to the expectations of their performance? To better understand the root causes and problems leading to executive hiring failure, we conducted a formal research project examining 225 executive level hires in 134 companies. This study was supplemented through an additional 20,000 CEO interviews over 15 years and an extensive secondary review of the available research on this topic. We limited our examination to the ten most commonly identified mistakes.