As demographics and buying power in the United States become increasingly more diverse, forward-thinking boards are determining ways to gain more diversity of background, experience, and thought in the boardroom. Since 2004, the Alliance for Board Diversity (“ABD” or “we”) has been striving to increase the representation of women and minorities on corporate boards. Over the past 14 years, ABD has celebrated the movement forward on diverse board representation, but the fact remains that progress has been painfully slow. This study is the culmination of a multiyear effort organized by the Alliance for Board Diversity, collaborating with Deloitte for the 2016 and 2018 censuses, which has examined and chronicled the representation of women and minorities on public company boards of directors across America’s largest companies. Originally organized as a “snapshot” of board diversity, the data since accumulated over time has allowed for the development of information on trends relative to overall diversity as well as the comparative differences in rates of representation among minorities and women over a period of more than a decade. This 2018 Missing Pieces Report highlights the progress to date that has been made (or not) for women and minorities on corporate boards. While there have been a few gains for some demographic groups, advancement is still slow. This movement is also not representative of the broad demographic transformations that have been seen in the United States over the same period of time.