The Bureau is responsible for conducting a complete and accurate decennial census of the U.S. population. The decennial census is mandated by the Constitution and provides vital data for the nation. A goal for the 2020 Census is to count everyone once, only once, and in the right place. Achieving a complete and accurate census is becoming an increasingly complex task, in part because the nation's population is growing larger, more diverse, and more reluctant to participate. When the census misses a person who should have been included, it results in an undercount. Historically, certain sociodemographic groups have been undercounted in the census, which is particularly problematic given the many uses of census data. Chapter 1 reviews the Bureau's plans for enumerating hard-to-count groups in the 2020 Census. The remaining chapters report on the reasons the 2020 Census remains on the High-Risk List and the steps the Bureau needs to take to mitigate risks to a successful census.