New policy efforts to support transition-aged foster youth (TAY) were implemented through the 2008 Federal Fostering Connections to Success Act in response to studies showing a) that foster youth who exit the child welfare system at 18 struggle in multiple domains during the transition to adulthood, and b) extended foster care supports through age 21 are associated with improved adaptation. However, there remains a need to clarify factors that influence policy uptake by TAY. Youths' and workers' satisfaction with the foster care service provision process may influence youths' decision making regarding whether or not to opt out of extended care and the quality of social workers' service provision, respectively. This study examined communication characteristics between TAY and their social workers as related to youth- and worker-reported satisfaction and relationship quality. Youth-worker dyads (N = 51; M=18.69 years, SD = .44; 56.9% female) were audio-recorded during a routine monthly meeting. Instrumental and affective communication features were rated in 5-minute samples of full speech, verbal content (i.e., transcripts), and non-verbal tone (i.e., content filtered speech). Principle Component Analyses (PCA) identified primary communication factors of TAY and social workers. Bivariate analyses revealed significant correlations among communication factors within and across channels, as well as with youths' and workers' reported satisfaction and perceived relationship quality. Youth expressed their true feelings about their workers and foster care in their full speech, and, relatedly, workers were most attuned to features of youth communication present in full speech. In contrast, workers expressed their true feelings about the youth in the content of their speech, and relatedly, youth were most attuned to features of worker communication present in the transcribed content of workers' speech. At the dyadic level, planned contrasts evaluated the importance of communicative congruence between workers and youth. Workers were responsive to congruence in positivity, whereas youth were more responsive to congruence in negativity. These findings highlight the relevance of communication-based research and training for applied efforts to support TAY in and beyond the child welfare system.