Purpose: To measure oral health (OH) knowledge, attitude and practices (KAP) of primary school teachers and to evaluate the relationship between these measures and oral health-related quality of life (OHRQoL). Materials and Methods: A total of 1013 school teachers from all regions of Kuwait were randomly selected in this cross-sectional study. A questionnaire on demographics, knowledge, attitude, practices and OHRQoL was used. Frequencies and means (SD) were used for data description. Correlations between KAP and OHRQoL were evaluated using Pearson's correlation coefficient. Associations between practice-specific knowledge and its corresponding practice as well as knowledge and practices and OHRQoL were determined using the chi-squared test. Results: About 71% of the participants were females, 57% were 30-50 years old, and 75% had a college education. The mean (95%CI) knowledge score was 60.2% (57.2-62.0), ranging from 15.4% to 93%. The well-known OH facts were the importance of brushing twice a day with fluoridated toothpaste, the cariogenic effect of sticky, sugary foods and snacks, as well as the damage that soft drinks can cause to teeth. The least known facts were replacement frequency of toothbrush, parent's supervision of children's brushing and the benefit of regular flossing. Weak but significant correlations were found between KAP components and OHRQoL (p 0.05). All practice-specific OH knowledge was significantly associated with its practice, except brushing and flossing (p > 0.05). Self-esteem was the mostly frequently affected OHRQoL construct by improper OH practices. Conclusion: Oral health knowledge by itself is not enough to change improper OH practices. Developing behaviourchanging interventions based on OHRQoL outcomes may be beneficial. Keywords: behavioural science, dental education, dental health perceptions, oral hygiene, quality of life