This study examined the budget allocation patterns of U.S. households during the period 2000–2015. Four household groups—classified based on their income levels in relation to the federal poverty level—are used for the analyses. Data from the quarterly interview component of the BLS Consumer Expenditure Survey were used in order to calculate households' annual expenditures in eight commodity groups: food, utilities, apparel and apparel services, transportation, medical care, shelter and household operations, other nondurable expenditures and services, and durable goods. An exact affine stone index (EASI) demand system was used to estimate demand relationships (i.e., price, income elasticities, and marginal effects). Overall, we find that budget allocation, consumers' responses to changes in prices and income, and the effects of sociodemographic characteristics on spending can be markedly different between income groups. The use of a representative or average household for demand analyses can mask substantial differences in economic behaviors between these four income groups.