We examined the influence of income source within the context of persistent poverty on children's disruptive classroom behavior at age 12 and whether these associations were mediated by maternal supervision at ages 10 and 11. Using a subsample (N = 1,112) from the Quebec Longitudinal Study, we coded four economic circumstances indicating persistent poverty (income-to-needs ratio less than 1.5 times the poverty line) and income source (working poor, welfare dependent, work and welfare dependent, vs. never poor working) from ages 8 through 11. Children in welfare-dependent families showed an increase of 2.23 points on the disruptive scale compared with children in never-poor families, which could not be prospectively explained by maternal supervision. These results are above and beyond the influence of family structure, maternal characteristics, and early childhood disruptiveness. (Contains 3 figures and 1 table.)