For individuals suffering from post-traumatic stress disorder (PTSD), the emotional numbing and isolation that are core aspects of their suffering often remain after initial treatments. The proposed study examined whether CBCT (Cognitively-Based Compassion Training), a secularized compassion program based on the Indo-Tibetan Buddhist lojong tradition, is effective for reducing emotional numbing and enhancing social connectedness in veterans with PTSD. To this end, we recruited twenty male veterans diagnosed with PTSD who continued to report emotional numbing symptoms even after exposure therapy. Prior to, and again after 10 weeks of CBCT, we measured patients’ emotional numbing and PTSD symptoms, relationship quality, compassion for self and for others, and engagement with CBCT. In addition, we assessed the quality and quantity of their real-world social behavior using an unobtrusive device that randomly records ambient sound. Almost half of the patients dropped out of the study prior to the intervention, highlighting the challenges facing veterans with PTSD. However, participants who attended the CBCT classes reported a high degree of engagement and satisfaction with the intervention, and they experienced a significant decrease in emotional numbing and PTSD symptoms following the intervention. The results support the feasibility and clinical benefit of CBCT for veterans with PTSD.