Parents can influence children's emotional responses through direct and subtle behavior. In this study we examined how parents' acute stress responses might be transmitted to their 7- to 11-year-old children and how parental emotional suppression would affect parents' and children's physiological responses and behavior. Parents and their children (N = 214; Ndyads = 107; 47% fathers) completed a laboratory visit where we initially separated the parents and children and subjected the parent to a standardized laboratory stressor that reliably activates the body's primary stress systems. Before reuniting with their children, parents were randomly assigned to either suppress their affective state-hide their emotions from their child-or to act naturally (control condition). Once reunited, parents and children completed a conflict conversation and two interaction tasks together. We measured their sympathetic nervous system (SNS) responses and observed interaction behavior. We obtained three key findings: (a) suppressing mothers' SNS responses influenced their child's SNS responses; (b) suppressing fathers' SNS responses were influenced by their child's SNS responses; and (c) dyads with suppressing parents appeared less warm and less engaged during interaction than control dyads. These findings reveal that parents' emotion regulation efforts impact parent-child stress transmission and compromise interaction quality. Discussion focuses on short-term and long-term consequences of parental emotion regulation and children's social-emotional development. (PsycInfo Database Record (c) 2020 APA, all rights reserved).