The New York City (NYC) Longitudinal Study of Wellbeing, or “Poverty Tracker,” is a survey of about 2,300 New York City residents. Its purpose is to provide a multidimensional and dynamic understanding of economic disadvantage in NYC. Measures of disadvantage were collected at baseline and a 12-month follow-up, and include three types of disadvantage: (1) income poverty, using a measure based on the new Supplemental Poverty Measure; (2) material hardship, including indicators of food insecurity, housing hardship, unmet medical needs, utility cutoffs, and financial insecurity; and (3) adult health problems, which can drain family time and resources. This paper presents initial results for NYC families with children under 18. At baseline, 56% of families with children had one or more type of disadvantage, including 28% with income poverty, 39% with material hardship, and 17% with an adult health problem. Even among nonpoor families, 33% experienced material hardship and 14% reported an adult health problem. Two-thirds of all families faced disadvantage at either baseline or follow-up, with 46% experiencing some kind of disadvantage at both time points. Respondents with a college education were much less likely to face disadvantage. Even after adjusting for educational attainment and family characteristics, the families of black and Hispanic respondents had elevated rates of disadvantage. Considering income poverty alone greatly understates the extent of disadvantage among families with children in New York City. These results suggest that in addition to addressing income poverty, policymakers should give priority to efforts to reduce material hardship and help families cope with chronic physical or mental illness. The need for these resources extends far above the poverty line.