BACKGROUND: Keeping older adults healthy and active is an emerging challenge of an aging society. Despite the importance of personal relationships to their health and well-being, changes in family structure have resulted in a lower frequency of intergenerational interactions. Limited studies have been conducted to compare different interaction style of intergenerational interaction. The present study aimed to compare the changes in visual attention, facial expression, engagement/behaviour, and intergenerational conversation in older adults brought about by a performance-based intergenerational (IG) program and a social-oriented IG program to determine a desirable interaction style for older adults. METHODS: The subjects of this study were 25 older adults who participated in intergenerational programs with preschool children aged 5 to 6 years at an adult day care centre in Tokyo. We used time sampling to perform a structured observation study. The 25 older participants of intergenerational programs were divided into two groups based on their interaction style: performance-based IG program (children sing songs and dance) and social-oriented IG program (older adults and children play games together). Based on the 5-minute video observation, we compared changes in visual attention, facial expression, engagement/behaviour, and intergenerational conversation between the performance-based and social-oriented IG programs. RESULTS: Constructive behaviour and intergenerational conversation were significantly higher in the social-oriented IG programming group than the performance-based IG programming group (p<0.001). No significant differences were observed in frequency of smiles, however, when weighted smiling rate was used, smiles were significantly more frequently observed in the social-oriented IG programming group than the performance-based IG programming (p<0.05). The visual attention occurred between the generations was significantly higher in the performance-based IG programming group than the social-oriented IG programming group (p<0.05). CONCLUSIONS: Intergenerational programs with preschool children brought smiles and conversation to older adults. The social-oriented IG program allowed older adults to play more roles than the performance-based IG program. The intergenerational programs provide opportunities to fulfil basic human needs and reintegrate older adults into society. Further development of such beneficial programs is warranted. TRIAL REGISTRATION: UMIN-CTR clinical Trial: UMIN000010439.