Objective: Family environments have an effect on physical health during adolescence, and a possible underlying mechanism is inflammation. However, little is known about the association between observed parenting behaviors and immune system functioning. The current study examined whether positive and negative emotional parental behaviors observed during family interactions were associated with inflammation in adolescents. Method: Sixty-one parent-adolescent dyads (37 male adolescents, 60.6%; 15 male parents, 24.6%) were observed during 2 laboratory-based interaction tasks designed to elicit positive and conflictual emotional behaviors, respectively. Frequency of aggressive and positive parental behavior was coded. Adolescents were followed up approximately 2.5 years later and salivary concentrations of the inflammatory biomarker C-reactive protein (sCRP) were measured. Results: Controlling for BMI and depressive symptoms, lower sCRP was associated both with greater frequency of positive parental behaviors, t = −3.087, p = .003 and less frequency of aggressive parental behavior (t = 2.087, p = .041) in the conflictual task. Trend associations between positive behavior during the positive task and lower sCRP were also found. Conclusions: This is the first study to show that observed positive parenting is associated with lower levels of inflammation in adolescents.