This study examined the effects of a 20-week intervention to foster affective involvement during interaction and communication between an adult with congenital deafblindness (CDB) and his caregivers in a group home and a daytime activities center. Using a single-subject design, we examined whether the intervention increased affective involvement between the participant and his caregivers, and whether the participant's positive emotions increased and his negative emotions decreased. In both settings, an increase in affective involvement and very positive emotions coincided with the onset of the intervention, with the clearest effects in the daytime activities center. Negative emotions decreased in the daytime activities center. During follow-up, affective involvement decreased in both settings but remained above baseline. The caregivers indicated that it was easier to share positive emotions than negative emotions. This study demonstrates that it is possible to foster affective involvement with an adult with CDB, both during interaction and communication.