The COVID-19 pandemic has financial and emotional impacts on families. We explored how caregivers’ financial strain and mental health are associated with changes in their young children’s behavior during the pandemic. We additionally considered whether having a sense of purpose moderated these associations. Caregivers (n = 300) in the emergency department of a children’s hospital were surveyed anonymously about changes to their employment (e.g., reduced/increased hours and job loss), ability to pay for expenses and whether their child’s behavior had changed. Aligned with the Family Stress Model, caregivers’ financial strain was associated with poor mental health, inconsistent sleep routines, and changes in children’s problematic and prosocial behaviors. A sense of purpose buffered some of these relationships. Families are differently affected by the pandemic and our findings underscore the need for supporting caregivers’ mental health and connecting them with resources.