Purpose: The purpose of this study was to do a preliminary examination of effects of an Institution-based Group Walking Program (IGWP) on affect and depression, wandering and other behavioral and psychological symptoms of dementia (BPSD), and sleep in persons with dementia (PWDs) who wander. Methods: This study used an A (baseline measure)- B (treatment condition)- A (baseline measure)- B (treatment condition) single case research design (n=10). Participants (mean MMSE=11.11±7.56; mean age=81±6.27) were encouraged to walk in a group along the pre-planned path every evening after supper for 30 minutes from Monday to Friday. Data were collected for four weeks: every day for affect and sleep; every week for wandering, BPSD, and depression. Using repeated measure ANOVA, within-subject effects and within-subject contrasts were evaluated. Results:　Within-subject effect was found on wanderer's affect (F=12.73, p =.001), depression (F=5.26, p =.005), neuropsychiatric symptoms (F=5.87, p =.016), hours of sleep (F=3.99, p =.018), sleep efficiency (F=3.99, p =.018), and frequency of wake-ups during sleep (F=5.05, p =.007). Conclusion: Results of this study imply that a regular group walking program may be beneficial for improving affect, mood, and night time behavior of wanderers. Further studies with larger samples and longitudinal design are necessary to confirm the findings obtained in this study.