Smoking inside home affects the health of a direct smoker and family members with second-hand exposure. The current research examined the effects of community participation program on smoke-free home in semi-urban community in Thanyaburi district of Pathumthani province in Thailand. Population included members of families with smokers, in respective area of the local administration organization of Thanyaburi municipality, including Lum Pak Kut and Rangsit sub-districts. The sample was randomly assigned for intervention and comparison groups, each containing 27 families. The intervention group was administered with the program for 5 sessions during the 6 month-period of study. The program contained the following components: community committee’s participation in decision making to solve the problem of smoking inside home; formulating smoke-free home policy; making action plans; smoke-free home campaign and public relations in community; educating family members about dangers of smoke and secondhand smoke and establishing smoking ban home rule; participation with the research team to practice skills in negotiating with smokers for smoking-ban inside home; giving emotional support for non-smoking inside home; posting smoke-free home stickers; giving advice about sources of help in need of smoking cessation. The comparison group was normally treated by community committee and health volunteers. Data collection was undertaken before implementation and 6 months after implementation by means of response to structured interview form. Skills in negotiating with smokers for no smoking inside home were evaluated. Emotional support was provided for non-smoking inside home. Comparisons were made on proportion of having smoking-ban home rule, and proportion of having smoke-free homes between the intervention and comparison groups. Data analyses were performed using descriptive statistics and test of hypotheses with Chi-Square test, paired t-test, independence t-test, and Fisher’s Exact test. Research results suggest that after the implementation, the intervention group reported significantly higher mean score of skills in negotiating with smokers for smoking-ban inside home and mean score of emotional support for non-smoking inside home than those before implementation and those of comparison group (p < 0.05). The proportion of having smoking ban home rules in intervention group was significantly higher (p < 0.05) than that before implementation and that of comparison group (92.6% versus 18.5%). The proportion of smoke-free home was higher in intervention than comparison group (75% versus 0%) which was significantly higher than that before implementation and that of the comparison group (p < 0.05). The current research suggests that community participation program for smoke-free home was effective in raising awareness on the impact of secondhand smoke on family members and in working together to manage for smoke-free home environment. The program was thus applicable for further development of community to achieve smoke-free homes.