The difference between immigrants' and natives' use of welfare program
s is concentrated among the elderly. This paper examines the determina
nts of immigrants' welfare participation decisions to evaluate the con
sequences of changes in immigration and welfare policy. An important f
inding for immigration policy is that immigrants who arrive after age
55 are significantly more likely to use welfare than the typical immig
rant who arrives during prime working years. Surprisingly, this age-at
-arrival effect is not explained by differences in Social Security ben
efits between young arrivers and old-arrivers. The problem of immigran
t welfare use is not simply low incomes or poor labor market performan
ce: decisions regarding takeup of benefits are an important explanatio
n for the effect of age at arrival. Finally, the sharp rise in immigra
nts' use of welfare during the 1980s was due mostly to higher welfare
participation rates of new immigrants.