© 2019, Emerald Publishing Limited. Purpose: The purpose of this paper is to examine the relationship between patients’ provider communication effectiveness and courteousness with patients’ satisfaction and trust at free clinics. Design/methodology/approach: This cross-sectional survey (n=507), based on the Consumer Assessment of Healthcare Providers and Systems instrument, was conducted in two Southeastern US free clinics. Latent class analysis (LCA) was used to identify patient subgroups (clusters) with similar but not immediately visible characteristics. Findings: Across the items assessing provider communication effectiveness and courteousness, five distinct clusters based on patient satisfaction, trust and socio-demographics were identified. In clusters where communication and courteousness ratings were consistent, trust and satisfaction ratings were aligned with these domains, e.g., 54 percent rated communication and courteousness highly, which was associated with high patient satisfaction and trust. When communication effectiveness and courteousness ratings diverged (e.g., low communication effectiveness but high courteousness), patient trust and satisfaction ratings aligned with communication effectiveness ratings. In all clusters, the association was greater for communication effectiveness than for provider courteousness. Thus, provider courteousness was important but secondary to communication effectiveness. Practical implications: Investment in patient-centered communication training for providers will improve patient satisfaction and trust. Originality/value: The study is the first to examine individual provider communication components and how they relate to patient satisfaction and trust in free clinics. LCA helped to more fully examine communication constructs, which may be beneficial for more nuanced quality improvement efforts.