From the Introduction: "This report will first briefly describe the scope of the underemployed population, and then it will illustrate how the percentages of underemployed persons, unemployed persons, and persons below poverty have risen and fallen over the course of previous business cycles. Next, the report will describe the wage rates by family size for which part-time jobs (such as those held by underemployed workers) are sufficient for staying out of poverty, and when they fall short. The last portion of the report will examine the connection between underemployment and poverty using three types of comparisons:  examining workers and nonworkers aged 18 to 64 by 'depth of poverty'--how far above or below the poverty threshold one's income is--focusing on the poverty status of the individual workers or nonworkers themselves;  examining poverty status by types of workers in a given family, to capture the potential for family members' work statuses to affect the poverty status of all family members; and  comparing poverty rates by both the number and type of workers present in the family."
CRS Report for Congress, R46939
Congressional Research Service: https://crsreports.congress.gov/