•First peer-reviewed study on foster parents’ ACEs and their relation to foster children’s social-emotional challenges.•Eighty-nine foster parents completed the ACE Questionnaire and the Strengths and Difficulties Questionnaire.•Twenty percent of foster parents reported 4+ ACEs, compared to 12.5 % in the original CDC-Kaiser study.•Foster parents’ ACEs were directly related to children’s conduct problems and hyperactivity-inattention, but not to peer or prosocial problems.•Increased challenging behaviors among foster children were related to several specific foster parents’ ACEs, such as emotional abuse. Adverse childhood experiences (ACEs) are known risk factors for negative health and behavioral outcomes, including caregiving. Foster parents are key to supporting foster children, yet there is limited research on their ACE history and how it might relate to their foster children’s behavior. This study addressed three research questions: (1) What are ACE totals in this sample of foster parents and how do they compare with the original CDC-Kaiser study? (2) Does foster parents’ ACE exposure relate to foster child behavior? (3) Is the relation between foster parents’ ACEs and children’s challenging behaviors different based on the specific ACE? Participants were 89 foster parents (age M = 43.3 years) and 50 of their foster children (age M = 10 years) in central Texas. Children have been in their current placements for an average of 11 months (range 1 month to 4.7 years). Foster parents completed demographics, the ACE Questionnaire (Felitti et al., 1998) and the Strengths and Difficulties Questionnaire (Goodman, 1997). Results showed over 40 % of foster parents in this sample reported 2+ ACEs and 20 % reported 4+ ACEs. Foster parents’ total ACEs related to foster children’s emotional problems (β = .27, p = .02), conduct problems (β = .28, p = .01), and hyperactivity-inattention (β = .25, p = .03). Certain ACEs related more strongly to child outcomes than others. Foster parents may have a higher ACE exposure than the general population. Foster parents’ ACEs were associated with foster children’s challenging behaviors. Future research should investigate the mechanism of this connection.