High conflict and low warmth in families may contribute to immune cells developing a tendency to respond to threats with exaggerated inflammation that is insensitive to inhibitory signaling. We tested associations between family environments and expression of genes bearing response elements for transcription factors that regulate inflammation: nuclear factor kappa B (NF-κB) and glucocorticoid receptor. The overall sample (47 families) completed interviews, questionnaires, and 8-week daily diary assessments of conflict and warmth, which were used to create composite family conflict and warmth scores. The diaries assessed upper respiratory infection (URI) symptoms, and URI episodes were clinically verified. Leukocyte RNA was extracted from whole blood samples provided by a subsample of 42 children (8–13 years of age) and 73 parents. In children, higher conflict and lower warmth were related to greater expression of genes bearing response elements for the proinflammatory transcription factor NF-κB, and more severe URI symptoms. In parents, higher conflict and lower warmth were also related to greater NF-κB–associated gene expression. Monocytes and dendritic cells were implicated as primary cellular sources of differential gene expression in the sample. Consistent with existing conceptual frameworks, stressful family environments were related to a proinflammatory phenotype at the level of the circulating leukocyte transcriptome.