Objectives: To describe how physical therapy providers and their patients interact and communicate about physical activity (PA), and explore the barriers and facilitators to patient involvement in PA programs. Method: We conducted 39 direct observations of patient visits with physical therapy providers and 30 telephone interviews with physical therapists (PTs). We conducted a thematic analysis of observation field notes and interview transcripts. Results: PTs and patients engaged in several behaviors to build rapport, discussed PA type and frequency, and exchanged advice and information about PA. Barriers to patient participation in PA programs included low instrumental support, physical limitations, lack of motivation and confidence, and lack of knowledge about available programs. Facilitators included emotional support from friends, peers, and family, and encouragement and information-sharing from providers. Discussion: PTs play an important role in improving older adult PA and could be instrumental in reducing barriers to PA participation.