We examined if and how laughter functioned communicatively as an indicator of engagement in group interactions involving adults with traumatic brain injury (TBI). Engagement refers to the intensity and manner of interpersonal involvement displayed by participants in social situations, and it reflects the extent to which they are mutually engrossed in, and alive to, the unfolding interaction. Analysis revealed that laughter functioned communicatively to support the "face," or public self-image, of those with TBI and to foster rapport and social closeness. The distribution of laughables, or verbal and nonverbal behaviors that occasion laughter, between participants was also examined and compared with data collected by Simmons-Mackie and Schultz in their analysis of humor during traditional aphasia therapy. Results revealed that laughter and laughables are sensitive to how individuals engage one another in interaction. Implications are considered with respect to more recent models of intervention that seek to promote more discourse equality between participants.