Understanding how youth perceive household economic hardship and how it relates to their behavior is vital given associations between hardship and behavioral development. Yet, most studies ignore youth’s own perceptions of economic hardship, instead relying solely on caregiver reports. Moreover, the literature has tended to treat economic hardship as a stable force over time, rather than a volatile one that varies month-to-month. This study addressed extant limitations by collecting monthly measures of economic hardship, specifically caregiver- and youth-reported material deprivation and youth-reported financial stress, and youth internalizing and externalizing problems from 104 youth–caregiver dyads (youth: 14–16 years, 55% female, 37% Black, 43% White) over nine months. We examined month-to-month variability of these constructs and how youth-reports of material deprivation and financial stress predicted their behavior problems, controlling for caregiver-reports of material deprivation. We found that hardship measures varied month-to-month (ICCs = 0.69–0.73), and youth-reported material deprivation positively predicted internalizing when examining both within- and between-individual variability (β = .19–.47). Youth-reported financial stress positively predicted within-individual variation in externalizing (β = .18), while youth reports of material deprivation predicted externalizing when looking between families (β = .41). Caregiver-reported material deprivation was unrelated to youth behavior when accounting for youth perceptions of economic hardship.