Introduction: Several studies have a well-documented positive association between sense of humor and physical and mental well-being in later life. However, there is evidence to indicate that sense of humor declines with age. This study was conducted to examine humor training program on the sense of humor among older adults. Methods: This community-based randomized controlled trial study was conducted in 2019. There were 18 older adults in the intervention group and 20 older adults in the control group. The intervention group received the 7 Humor Habits Program in eight training sessions, whereas the control group was waitlisted. The Multidimensional Sense of Humor Scale (MSHS) was used to measure the sense of humor before and after the intervention. A series of paired samples t-tests and difference-in-differences approach using IBM SPSS Version 23.0 were conducted to assess changes from pre-test to post-test. The significance level of p ≤ .05 was considered for the statistical analysis. Results and Discussion: The mean age of the participants in the intervention and control groups was 66.50, (SD=6.14) and 67.60, (SD= 5.64) years, respectively. The results of a series of paired samples t-tests revealed a statistically significant increase in the total score of sense of humor from pre-test (M =77.28, SD = 13.62) to post-test (M=101.11, SD=17.06), (t= -6.77, p<.001), in intervention group. Other paired samples t-tests showed statistically significant changes from pre-test to post-test for subscales of humor including enjoyment of humor (t= -4.59, p<.001), laughter (t= -7.83, p<.001), verbal humor (t= -4.73, p<.001), finding humor in everyday life (t= -4.19, p<.001), laughing at yourself (t= -6.36, p<.01), and humor under stress (t= -2.54, P≤.05) in intervention group. Moreover, the results of the difference-in-differences approach revealed a significant increase in the sense of humor for the intervention group compared to the control group (F=43.54, p<.001). No statistically significant changes were observed in any outcome variables in the control group. Conclusion: The results of this study provided support that the sense of humor can be improved using a training program in later life.