Income data are available from many sources including surveys, tax records, and administrative data from government programs. When used alone, each of these sources has important strengths and major limitations. While previous research has combined some sources of income to address these drawbacks, the scope and generalizability of these efforts are limited. To address this gap, we are developing the Comprehensive Income Dataset (CID), a micro-level dataset with population-level income and demographic characteristics that will provide an accurate and comprehensive measure of income for the population of U.S. families and households and include associated information on program participation and tax credit receipt. The CID will be far and away the best source to analyze poverty, inequality, mobility, and the distributional consequences of government transfers, taxes and tax credits, as well as numerous additional research topics.