BACKGROUND: Information on the impact of oral health on quality of life of children younger than 8 years is mostly based on parental reports, as methodological and conceptual challenges have hindered the development of relevant validated self-reported measures. This study aimed to develop and assess the reliability and validity of a new self-reported oral health related quality of life measure, the Scale of Oral Health Outcomes for 5-year-old children (SOHO-5), in the UK. METHODS: A cross-sectional study of two phases. First, consultation focus groups (CFGs) with parents of 5-year-olds and review by experts informed the development of the SOHO-5 questionnaire. The second phase assessed its reliability and validity on a sample of grade 1 (5-year-old) primary schoolchildren in the Greater Glasgow and Clyde area, Scotland. Data were linked to available clinical oral health information and analysis involved associations of SOHO-5 with subjective and clinical outcomes. RESULTS: CFGs identified eating, drinking, appearance, sleeping, smiling, and socialising as the key oral impacts at this age. 332 children participated in the main study and for 296 (55% girls, mean d3mft: 1.3) clinical data were available. Overall, 49.0% reported at least one oral impact on their daily life. The most prevalent impacts were difficulty eating (28.7%), difficulty sleeping (18.5%), avoiding smiling due to toothache (14.9%) and avoiding smiling due to appearance (12.5%). The questionnaire was quick to administer, with very good comprehension levels. Cronbach's alpha was 0.74 and item-total correlation coefficients ranged between 0.30 and 0.60, demonstrating the internal consistency of the new measure. For validity, SOHO-5 scores were significantly associated with different subjective oral health outcomes (current toothache, toothache lifetime experience, satisfaction with teeth, presence of oral cavities) and an aggregate measure of clinical and subjective oral health outcomes. The new measure also discriminated between different clinical groups in relation to active caries, pulp involvement, and dental sepsis. CONCLUSIONS: This is the first study to develop and validate a self-reported oral health related quality of life measure for 5-year-old children. Initial reliability and validity findings were very satisfactory. SOHO-5 can be a useful tool in clinical studies and public health programs.