This study investigated how marriage, cohabitation, single parenthood, and the presence of biological parents affected the incomes and material hardships of children. Data from the 1997 and 1999 National Survey of America's Families were used to examine recent changes in the marital status and household structure of families with children, how levels of income and material hardship varied by family structure, and whether marriage acted to reduce marital hardship, even among families with low incomes and among children of less-educated mothers. Results indicated that net of education, race, immigrant status, age, and age and number of children, married couple families achieved significantly lower poverty levels than other family types, including families with at least two potential earners. Even among the poor, material hardships were significantly lower among married couple families with children than among other families with children, including those with at least two potential earners. Marriage impacts were quite large, and generally higher than the effects of education. Impacts were particularly high among non-Hispanic black families. (Contains 14 tables and 21 references.) (SM)